A  K  o]')0]i  f  o  the  DktHei  Engbeer, 
U-     Erif  kofer- Off  ice,  Ghita^o 


DATE  DUE 


ISWS 
B 

23 

Loan  c.  1 
05041003 

Aivoru,  Duruit/K  oc  nvwov^xi 
THE  DISPOSAL  OF  THE 
SEWAGE  OF  THE 
SANITARY  DISTRICT  OF 
CHICAGO. 

ILLIHOlSSTi^T 

1 — 

ISWS  Alvord,  Burdick  &  Howson 

B  THE  DISPOSAL  OF  THE 

23  SEWAGE  OF  THE 

Loan  SANITARY  DISTRICT  OF 

c.  I  CHICAGO. 

05041003 


pEMCO 


/ 


STATE  OF  ILLINOIS 
DEPARTMENT  OF  REGISTRATION  AND  EDUCATION 

DIVISION  OF  THE 

STATE  WATER  SURVEY 

A.  M.  BUSWELL,  Chief 


BULLETIN  NO.  23 


THE  DISPOSAL  OF  THE  SEWAGE  OF 
THE  SANITARY  DISTRICT 
OF  CHICAGO 

A  Report  to  the  District  Engineer 
U.  S.  Engineer  Office,  Chicago 

BY 

ALVORD,  BURDICK  &  HOWSON,  Engineers 


[Printed  by  authority  of  the  State  of  Illinois] 

URBANA,  ILLINOIS 


CONTENTS 


Page 

Organization   ,  iv. 

Letter  of  transmittal  v. 

Letter  of  authorization  vi. 

Part  I.      — Introduction,  summary  and  conclusions   1 

Part  II.    — Present  disposal  of  sewage  and  deficiencies   12 

Part  III.  — Population  and  growth   39 

Part  IV.  — Amount  and  quality  of  sewage   48 

Part  V.     — Standard  of  maximum  pollution   64 

Part  VI.    — Required  degree  of  purification  with  various  dilutions.  79 

Part  VII.  — Protection  of  the  water  supply   85 

Part  VIII. — Savings  effected  by  metering  101 

Part  IX.    — Volume  of  sewage  114 

Part  X.  - — Future  intercepting  sewer  construction  119 

Part  XI.   — Methods  of  sewage  disposal  and  practicable  efficiencies  128 

Part  XII.  — Sewage  disposal  costs  in  other  cities  145 

Part  XIII. — Required  works  for  10,000  cubic  feet  per  second  flow.  170 
Part  XIV. — Required  works  with  4,167  cubic  feet  per  second  flow.  174 

Part  XV.  — Required  works  with  miscellaneous  flows  180 

Part  XVI. — Review  of  expenditures  under  various  flows  185 


PHILLIPS  BROS.-  PRINT. 
SPRINGFIELD.  ILLINOIS. 

1  9  °2  7 
(60418—1500) 


iii. 


ORGANIZATION. 


STATE  OF  ILLINOIS 
Len  Small,  Governor 

DEPARTMENT  OF  REGISTRATION  AND  EDUCATION 
A.  M.  Shelton,  Director 

Board  of  Natural  Resources  and  Conservation  Advisers 

A.  M.  Shelton,  Chairman 

William  A.  Noyes,  Chemistry,  Henry  C.  Cowles,  Forestry. 

Secretary.  William  Trelease,  Biology. 

John  W.  Alvord,  Engineering.  C.   M.    Thompson,    Representing  the 

Edson  S.  Bastin,  Geology.  President  of  the  University  of  Illi- 


nois. 


Water  Survey 


Division  Committee 


A.  M.  Shelton 

C.  M.  Thompson 


William  A.  Noyes 
John  W.  Alvord 


WATER  SURVEY  DIVISION 


A.  M.  Buswt:ll,  GTiief 


iv. 


LETTER  OF  TRANSMITTAL. 


State  Water  Survey  Division 

ARTHUR  M.  BUSWELL,  CHIEF 

Urbana,  III. 

February  18,  1927. 

A.  M.  Shelton,  Chairman,  and  Members  of  the  Board  of  Natural 
Resources  and  Conservation  Advisors: 

Gentlemen  :  Herewith  I  submit  a  report  on  the  disposal  of  the 
sewage  of  the  Sanitary  District  of  Chicago  and  recommend  that  it  be 
published  as  Bulletin  No.  23  of  the  State  Water  Survey  Division. 

This  report  was  prepared  by  Alvord,  Burdick  &  Howson,  consult- 
ing engineers,  of  Chicago,  by  order  of  the  Secretary  of  War  pursuant 
to  a  resolution  of  the  Committee  on  Rivers  and  Harbors  of  the  House 
of  Representatives,  U.  S.,  April  14th,  1924,  and  submitted  to  the  Dis- 
trict Engineer,  U.  S.  Engineer  Office,  Chicago. 

The  printing  of  this  report  as  a  Water  Survey  Division  Bulletin 
has  been  authorized  by  the  Secretary  of  War.  The  letter  granting  this 
authorization  is  included  herewith. 

The  material  presented  in  this  manuscript  contains  so  much  data 
on  the  cause  and  remedy  of  the  most  serious  stream  pollution  problem 
in  the  State  that  it  seems  highly  advisable  to  make  it  available  to  the 
citizens  of  the  State  in  published  form. 

Respectfully  submitted, 

A.  M.  Bus  WELL,  Chief. 


V. 


LETTER  OF  AUTHORIZATION. 


War  Department 
United  States  Engineer  Office 
537  South  Dearborn  Street 
Chicago,  Illinois 

October  25,  1926. 

Dr.  A.  M.  Buszvelly  Chief,  State  Water  Survey  Division,  Board  of 
Natural  Resources  and  Conservation,  Urbana,  Illinois, 

Dear  vSir  :  Your  request  for  permission  for  the  State  Department 
of  Registration  and  Education  to  print  the  report  of  Alvord,  Burdick  & 
Howson,  Engineers,  to  the  U.  S.  District  Engineer  on  the  Disposal  of 
the  Sewage  of  the  Sanitary  District  of  Chicago,  has  been  approved  by 
the  Chief  of  Engineers,  with  the  condition  that  Chapter  XII  be  also 
published,  and  that  credijt  and  acknowledgment  be  made  to  the  Chief  of 
Engineers  and  the  War  Department,  for  whom  and  under  whom  the 
report  was  prepared. 

Yours  very  truly, 

Edward  H.  Schulz, 
Colonel,  Corps  of  Engineers, 
District  Engineer. 


vi. 


PART  I. 


INTRODUCTION,  SUMMARY,  AND  CONCLUSIONS. 

District  Engineer, 

U.  S.  Engineer  Office, 
337  S.  Dearborn  St., 
Chicago,  111. 
Dear  Sir: 

Proceeding  under  our  instructions  of  January  16,  1925,  we  have 
studied  the  problem  of  sewage  disposal  for  the  City  of  Chicago  and 
vicinity,  including  more  particularly  that  territory  embraced  within  the 
Sanitary  District  of  Chicago. 

Our  study  has  been  particularly  directed  to  answers  for  the  fol- 
lowing questions : 

(a)  Determination  of  a  pollution  standard  for  the  Chicago  Drain- 
age Canal  for  each  of  the  following  average  diversions  from  Lake 
Michigan ;  —2,000,  4,167,  6,000,  7,500,  8,500  and  10,000  cubic  feet  per 
second ;  this  standard  to  be  the  lowest  that  will  prevent  the  occurrence 
of  nuisance  in  the  Des  Plaines  and  the  Illinois  River,  and  will  permit 
a  thriving  fish  life  therein. 

These  diversions  include  the  sewage  flow  of  the  Sanitary  District ; 
and  they  therefore  represent  the  dry  weather  flow  of  the  Drainage 
Canal  at  Lockport,  approximately. 

(b)  Determination  of  the  extent  to  which  purification  measures 
must  be  taken  by  the  Sanitary  District  of  Chicago  for  each  of  the  flows 
specified  above,  in  order  that  the  pollution  standard  be  maintained  unim- 
paired. 

(c)  Determination  of  the  most  feasible  method  of  treating  the 
surplus  pollution,  and,  for  each  flow  specified,  the  cost  of  the  necessary 
works  and  the  operating  costs  thereof. 

(d)  The  determination  of  the  time  that  reasonably  would  be  re- 
quired to  build  the  necessary  works  and  place  them  in  operation  for 
each  of  the  flows  specified. 

In  the  study  of  this  matter  the  time  at  our  disposal  has  not  per- 
mitted original  investigations.    It  has  been  possible  only  to  view  the 
present  situation  by  inspection,  and  to  study  the  large  amount  of  data 
that  has  been  accumulated  by  the  Sanitary  District  of  Chicago  and  . 
other  agencies,  bearing  directly  upon  the  answers  to  the  above  questions. 


2 


We  have  further  brought  to  bear  upon  the  study  of  the  problem  the  ex- 
perience of  other  cities  regarding  sewage  disposal,  insofar  as  informa- 
tion has  been  gained  that  would  throw  light  upon  the  Chicago  situation. 

Upon  the  pages  which  follow  we  have  stated  the  local  problem  in 
some  detail,  and  we  have  discussed  the  various  phases  of  it  insofar  as 
we  believe  is  required  for  a  general  understanding  of  the  problem,  and 
our  answers  to  the  questions  previously  stated.  For  the  benefit  of  those 
already  somewhat  familiar  with  this  problem  we  will  first  briefly  state 
our  summarized  findings  and  conclusions.  We  will  follow  this  statement 
by  a  more  detailed  consideration  of  the  problem,  and  a  further  state- 
ment of  the  conditions  and  the  reasons  leading  to  the  conclusions  stated. 

SUMMARIZED  CONCLUSIONS. 

1st.    Present  Disposal: 

The  diversion  of  the  Chicago  sewage  from  Lake  Michigan,  result- 
ing from  the  Drainage  Canal  and  other  causes,  has  effected  a  remark- 
able improvement  in  the  death  rate  from  water  borne  diseases.  The 
sewage  nuisance  in  the  streams  of  the  Chicago  district  has  been  re- 
duced^ to  a  large  extent. 

This  result  has  been  accomplished,  however,  by  transferring  the 
bad  conditions  in  Chicago  to  the  Des  Plaines  and  Illinois  Rivers  in 
which  a  crying  nuisance  has  been  created  for  more  than  one  hundred 
miles ;  and  by  diverting  large  amounts  of  water  from  the  Great  Lakes, 
over  strenuous  objections  from  property  owners  claiming  a  right  to  the 
water  diverted. 

It  is  generally  conceded  that  the  present  conditions  should  not  be 
allowed  to  continue.  The  Sanitary  District  is  already  engaged  upon 
remedial  measures  through  which  a  large  part  of  the  sewage  will  be 
treated  before  discharge  into  the  Drainage  Canal. 

2nd.    Population  and  Growth: 

In  planning  works  for  sewage  disposal,  it  is  necessary  to  consider 
the  future  population  of  the  locality.  It  is  not  financially  practicable 
to  make  expenditures  now  for  a  problematical  future.  It  is  necessary, 
however,  to  determine  the  future  populations  approximately  and  to 
adopt  works  capable  of  construction  in  units  that  may  be  increased  in 
capacity  from  time  to  time  as  occasion  requires,  without  destroying 
previous  expenditures.  Thus  each  dollar  expended  will  provide  a  link 
in  a  complete  chain  of  sewage  disposal  works. 

We  have  examined  the  forecast  of  population  as  estimated  by  the 
Sanitary  District  of  Chicago,  and  we  believe  it  represents  future  proba- 
bilities as  accurately  as  required  for  the  above  purpose.  This  estimate 
covering  the  population  of  the  Sanitary  District  is  as  follows : 


3 


1930 
1940 
1950 
1960 
1970 


1920  census, 


2,978,635 
3,710,000 
4,425,000 
5,140,000 
5,850,000 
6,580,000 


In  addition  to  the  population  in  the  Sanitary  District,  there  is  now 
(1925)  a  population  of  180,000  in  the  northern  Indiana  cities  bordering 
the  lake  and  draining  through  the  Calumet  River.   Under  ordinary  low 
flow  conditions  this  drainage  passes  through  the  Sag  Channel  to  the  ■ 
Main  Drainage  Channel  and  thus  into  the  Illinois  River. 

The  Sanitary  District  includes  about  eighty-five  per  cent  of  the 
total  population  in  the  greater  Chicago  region  which  includes  Cook, 
Kane,  DuPage,  Lake  and  Will  Counties  in  Illinois,  and  Lake  County  in 
Indiana.  The  greater  part  of  the  outlying  population  has  more  or  less 
effect  upon  the  pollution  of  the  lake  and  the  nearby  streams. 

3rd.    Amount  and  Character  of  Sewage: 

The  present  discharge  of  the  sewers  within  the  Sanitary  District 
is  about  800  miUion  gallons  per  day.  This  is  equivalent  to  a  river  100 
feet  wide  and  five  feet  deep  flowing  one  and  one-half  miles  per  hour. 

This  sewage  carries  an  organic  load  per  capita  greater  than  any 
other  large  city  for  which  accurate  figures  have  been  available  to  us. 
This  excessive  load  is  partly  due  to  a  few  great  industries  which  pro- 
duce an  'amount  of  pollution  estimated  by  the  Sanitary  District  to  be  the 
equivalent  of  about  1,500,000  people  (1920). 

4th.    Standard  for  Pollution: 

In  the  consideration  of  sewage  treatment  works  that  wifl  be  re-- 
quired  under  various  drafts  of  dilution  water  from  Lake  Michigan,  it 
has  been  necessary  to  fix  a  standard  of  maximum  pollution  for  the  Chi- 
cago Drainage  Canal  in  order  that  reasonable  sanitary  conditions  may 
be  maintained  in  the  Des  Plaines  and  Illinois  Rivers.  We  suggest  the 
following  as  a  reasonable  standard : 

The  liquid  discharged  by  the  Drainage  Canal,  as  evidenced  by 
the  average  of  representative  samples  taken  for  any  thirty  consecu- 
tive days  shall, 

(a)  Be  practically  free  from  settleable  solids  deposited  in 
two  hours,  and, 

(b)  Shall  contain  dissolved  oxygen  equal  to  or  exceeding  the 
biochemical  oxygen  demand  of  said  liquid  for  five  days  when  in- 
cubated at  20  degrees  C. 


4 


(c)    Shall  contain  not  less  than  three  parts  per  million  of  dis- 
solved oxygen. 

The  treatment  works  hereinafter  outlined  in  connection  with 
specified  dilutions  from  the  lake  will  meet  this  standard  in  our  opinion. 

5th.    Protection  of  the  Water  Supply: 

Even  under  the  heavy  diversions  from  Lake  Michigan  in  recent 
years  and  the  generally  favorable  typhoid  death  rate,  the  quality  of  the 
water  supply  for  Chicago  has  been  far  from  satisfactory.  This  is  due 
to  the  incidental  pollution  of  the  lake,  periodic  discharges  from  the 
Chicago  and  Calumet  Rivers  and  other  causes.  Occasionally  sporadic 
typhoid  outbreaks  have  occurred  attributable  to  the  water.  Safety  is 
only  secured  by  heavy  dosages  of  liquid  chlorine  which  are  extremely 
objectionable  to  many  people  and  which  the  Chicago  authorities  regard 
as  closely  approaching  the  maximum  dosage  tolerable. 

Compared  to  the  usual  standards  applicable  to  clean  water,  the 
water  is  dirty  most  of  the  time,  and  it  is  quite  turbid  more  than  ten 
per  cent  of  the  time.  Even  when  comparatively  clear  it  often  contains 
miscroscopic  animal  organisms  no  doubt  harmless,  but  very  objection- 
able to  many  people. 

The  filtration  of  drinking  water  has  been  extensively  practiced  for 
more  than  twenty  years.  More  than  twenty  million  people  are  thus 
supplied  in  the  United  States.  Many  filtration  plants  handle  a  water 
polluted  to  a  greater  degree  than  Lake  Michigan  water  would  be  under 
any  diversions  for  dilution  purposes  considered  in  this  report. 

Chicago  can  secure  pure  clean  water  at  all  times  by  the  filtration  of 
its  present  supply.  We  regard  this  as  the  only  means  by  which  a  satis- 
factory supply  of  water  may  be  obtained,  regardless  of  any  practicable 
measures  for  sewage  treatment  or  lake  water  diversions  for  dilution. 

Filtration  is  considered  as  a  pre-requisite  to  the  adequate  disposal 
of  sewage  in  all  projects  considered  in  this  report. 

6th.    Metering  of  the  Water  Supply: 

At  the  present  time  ninety  per  cent  of  all  water  services  in  Chicago 
are  served  through  so-called  ''flat  rates."  The  pumpage  of  water  is 
excessive,  pressures  are  deficient,  fire  protection  service  is  jeopardized 
and  the  costs  of  water  supply,  intercepting  sewers  and  sewage  disposal 
are  greatly  increased  over  what  would  be  necessary  if  water  waste  were 
restricted. 

Universal  metering  of  the  water  services  is  urgent.  Metering 
alone  will 

(a)    Double  the  average  pressure  within  the  City  of  Chicago. 


5 


(b)  Furnish  all  adequate  water  service  where  but  twenty-five 
percent  now  enjoy  it. 

(c)  Enable  the  present  water  works  with  but  minor  exten- 
sions to  serve  the  City  for  the  next  generation. 

(d)  Through  the  immense  savings  effected  in  deferred  con- 
struction costs  enable  the  City  to  install  filtration  works. 

If  universal  metering  of  the  Chicago  Water  Works  is  accomplished 
within  the  next  ten  years  savings  of  from  $200,000,000  to  $225,000,000 
will  be  effected  prior  to  1945.  This  amount  is  so  great  that  in  addition 
to  financing  the  installation  of  meters  and  filtration  works  for  the 
entire  city,  it  would  cover  the  cost  of  constructing  the  entire  intercept- 
ing sewer  and  sewage  disposal  works  required  in  the  Chicago  Sanitary 
District  up  to  1945  and  leave  a  large  surplus  in  addition. 

The  costs  of  sewage  disposal  are  also  influenced  by  the  waste  of 
water.  If  universal  metering  of  the  water  works  services  is  not  under- 
taken, the  estimated  costs  of  the  interceptors  and  sewage  treatment 
works  outlined  in  this  report  must  be  increased  by  an  amount  of  from 
$42,000,000  to  $53,000,000  depending  upon  the  flow  available  for  dilu- 
tion and  the  types  of  plants  required  thereby. 

7th.    Volume  of  Sezvage: 

The  total  quantity  of  sewage  to  be  treated  in  the  Chicago  District 
may  be  taken  as  approximately  equal  to  the  total  water  supply.  This 
assumes  that  infiltration  into  the  sewers  will  be  offset  by  that  part  of  the 
water  supply  used  for  sprinkling  and  other  purposes  which  do  not  con- 
tribute to  the  sewage  flow. 

At  the  present  time,  due  to  water  waste,  the  pumpage  of  water  in 
the  Chicago  District  is  excessive.  The  dry  weather  flow  of  sewage  is 
correspondingly  much  larger  than  it  would  be  if  the  waste  of  water  were 
curtailed. 

The  total  volume  of  sewage  under  metered  and  unmetered  condi- 
tions has  been  estimated  based  upon  the  assumption  that  a  ten  year 
period  beginning  in  1925  and  terminating  in  1935  will  be  required  to 
install  meters  on  all  water  services  in  the  City  of  Chicago,  and  that  when 
all  services  are  metered  the  sewage  per  capita,  including  industrial  and 
all  other  uses,  will  be  approximately  160  gallons  per  day. 

Under  these  assumptions  the  following  table  shows  the  estimated 
quantities  for  each  five  year  period  from  1925  to  1945. 


6 


Million  Gallons  Sewage  Daily. 

Present  Conditicns  Universal 


Year  of  Metering  Metering 
1925  877 

1930  1,054  777  (50%  metered) 

1935  1,243  662 

1940  1,437  711 

1945  1,629  769 


The  installation  of  meters  on  all  services  will  cause  the  sewage  flow 
of  1945  under  complete  metering  to  be  less  than  at  the  present  time, 
when  but  ten  percent  of  the  services  are  metered. 

8th.    Intercepting  Sezvers: 

The  Sanitary  District  has  adopted  tunnels  for  its  intercepting 
sewers.  This  appears  to  be  a  logical  conclusion  in  view  of  congestion 
on  the  ground  surface. 

Intercepting  sewers  have  been  built  or  are  under  construction  for 
all  areas  except  the  West  Side  and  the  Southwest  Side.  The  intercept- 
ing sewers  to  serve  these  two  areas  will  in  general  extend  along  both 
sides  of  the  main  channel  and  the  north  and  south  branches  of  the 
Chicago  River  beginning  with  Fullerton  Avenue  on  the  North  Side  and 
extending  in  a  southwesterly  direction  to  the  site  proposed  for  the  West 
and  Southwest  Side  plants  along  the  Drainage  Canal  near  Summit. 

It  is  beheved  that  with  universal  metering  these  intercepting  sewers 
should  be  designed  of  such  capacity  that  they  will  carry  a  flow  equiva- 
lent to  375  gallons  per  capita  per  day.  This  is  approximately  two  and 
one-third  times  the  average  flow  as  it  is  estimated  to  be  after  the  in- 
stallation of  meters. 

It  is  believed  that  a  35-year  period  (i.  e.  to  1960)  is  that  for  which 
the  design  of  interceptors  should  be  economically  and  practically  made 
for  sewers  constructed  in  tunnel,  capable  of  duplication  in  the  future 
without  excessive  costs. 

The  20  miles  of  intercepting  sewers  required  for  the  West  Side 
system  have  been  estimated  to  cost  $7,890,000. 

The  15  miles  of  sewers  required  for  the  Southwest  Side  plant  have 
been  estimated  to  cost  $4,495,700. 

9th.    Sezvage  Disposal  Costs  in  Other  Cities: 

Construction  and  operating  costs  of  sewage  pumping  stations  and 
treatment  works  in  other  cities  were  compared  with  similar  costs  in- 
curred by  the  Sanitary  District  of  Chicago  in  certain  works  already 
built. 

In  making  this  comparison  consideration  has  been  given  to  the 
price  basis  when  the  work  was  done  and  the  unit  costs  for  labor  and 
materials  in  the  cities  compared.  We  deduce  the  following  conclusions 
from  the  comparison : 


7 


(a)  Recent  intercepting  sewer  contract  costs  in  Chicago  have 
been  substantially  double  those  secured  in  other  cities  under  like  con- 
struction conditions. 

(b)  The  Calumet  Imhoff  tank  plant,  constructed  by  the  Sanitary 
District  of  Chicago  (after  being  credited  with  the  reasonable  cost  of 
an  experimental  sprinkHng  filter  and  activated  sludge  plant),  cost  ap- 
proximately three  tim.es  the  average  of  tank  plants  of  similar  type  in 
other  cities. 

(c)  The  Des  Plaines  activated  sludge  plant  of  the  Sanitary  Dis- 
trict of  Chicago  cost  approximately  three  times  the  average  cost  of 
similar  plants  in  Milwaukee  and  Indianapolis. 

(d)  The  cost  of  operating  the  Calumet  Imhoff  tank  plant  (after 
being  credited  with  the  reasonable  cost  of  operating  a  small  sprinkHng 
filter  and  a  small  activated  sludge  plant),  is  approximately  four  times 
that  of  operating  similar  plants  in  other  cities  when  compared  on  the 
basis  of  cost  per  million  gallons  treated  or  ten  times  the  average  based 
on  cost  per  capita  served. 

(e)  The  cost  of  operating  the  Des  Plaines  activated  sludge  plant 
of  the  Sanitary  District  of  Chicago  is  from  eight  to  ten  times  that 
estimated  to  be  necessary  for  the  operation  of  the  activated  sludge  plant 
at  Milwaukee. 

(f)  The  cost  of  operating  the  39th  St.,  Lawrence  Avenue  and 
Calumet  pumping  stations  of  the  Sanitary  . District  of  Chicago  is  approx- 
imately three  times  as  great  per  unit  of  work  performed  as  that  of  other 
stations  of  similar  size  and  type  in  other  cities. 

10th.    Basis  of  Cost  EsPimates: 

All  estimates  of  cost  of  construction  and  operation  used  herein  are 
predicated  upon  labor  and  material  prices  prevailing  in  the  Chicago 
District  in  the  early  part  of  1925.  The  estimates  are  further  based  upon 
the  average  efficiency  which  it  is  practicable  to  secure  in  public  enter- 
prises of  similar  nature ;  no  better  and  no  worse  than  conditions  recently 
prevailing  in  Detroit,  Cleveland  and  Milwaukee. 

11th.    Types  of  Treatment  Works: 

At  the  present  time  the  Des  Plaines  activated  sludge  plant  and  the 
Calumet  Imhofif  tank  plant  are  in  operation.  The  Sanitary  District  is 
also  definitely  committed  to  the  construction  of  an  activated  sludge  plant 
at  the  North  Side  plant,  the  construction  of  which  is  about  one-third 
completed. 

All  of  the  estimates  herein  made  for  all  amounts  of  flow  considered 
are  based  upon  the  Sanitary  District's  program  of  adding  sprinkling 
filters  at  the  Calumet  plant,  and  of  building  a  sprinkling  filter  plant  at 


8 


the  Corn  Products  Plant  and  an  activated  sludge  plant  at  the  Stock- 
yards. The  variations  in  degree  of  treatment  required  with  the  several 
flows  considered,  are  all  secured  herein  by  applying  different  treatment 
processes  to  the  West  and  Southwest  Side  plants. 

All  estimates  of  cost  herein  are  in  addition  to  contracts  now  let 
and  under  construction  on  the  North  Side  intercepting  sewerg  and  that 
part  of  the  North  Side  disposal  plant  for  which  contracts  have  thus  far 
been  let. 

In  our  opinion  the  sites  for  proposed  sewage  disposal  works  are 
well  chosen. 

12th.    Additional  Works  Required  zvith  10,000  Cubic  Feet  Per  Second 
Flozv: 

A  flow  in  the  channel  of  10,000  cubic  feet  per  second  will  necessi- 
tate in  addition  to  the  sewage  disposal  works  now  constructed  or  under 
contract,  preliminary  or  tank  treatment  of  the  sewage  at  the  West  Side 
plant  and  complete  tank  and  sprinkling  filter  treatment  for  the  South- 
west Side. 

The  cost  of  additional  purification  works  including  intercepting 
sewers  required  with  a  total  flow  of  10,000  cubic  feet  per  second  is  esti- 
mated at  $57,415,240  to  1935  and  $64,692,700  to  1945. 

The  cost  of  operation  of  all  pumping  stations  and  sewage  disposal 
plants  with  a  flow  of  10,000  cubic  feet  per  second  is  estimated  at 
$4,364,000  in  1935  and  $5,004,800  in  1945. 

13th.    Required  Works  zvith  4,167  Cubic  Feet  Per  Second  Flozv: 

With  a  smaller  amount  of  diluting  water,  complete  secondary 
treatment  of  the  sewages  at  both  the  West  and  Southwest  Side  plants 
would  be  necessary.  Tanks  and  sprinkling  filter  treatment  would  not 
be  suflicient  by  1945.  Activated  sludge  treatment  is  required  to  meet 
the  1945  conditions  with  but  4,167  c.  f.  s.  flow  available. 

The  estimated  cost  of  all  interceptors  and  disposal  plants  required 
with  the  flow  of  4,167  cubic  feet  per  second  is  $69,213,500  for  1935  con- 
ditions, and  $76,583,300  for  1945  conditions. 

We  estimate  the  cost  of  operating  all  sewage  pumping  stations  and 
sewage  disposal  plants  necessary  with  the  flow  of  4,167  cubic  feet  per 
second  at  $5,163,100  in  1935  and  $5,817,600  in  1945. 

14th.    Required  Works  zvith  2,000  Cubic  Feet  Per  Second  Flozv: 

With  a  flow  as  small  as  2,000  cubic  feet  per  second  there  is  no  prac- 
ticable way  of  meeting  the  pollution  standard  herein  suggested. 

15th.    Required  Works  zvith  7,500  Cubic  Feet  Per  Second  Flozv: 

The  7,500  cubic  feet  per  second  flow  requires  that  a  complete 
sprinkling  filter  plant  be  built  at  the  West  Side  and  tanks  at  the  South- 


9 


west  Side.  This  will  suffice  up  to  as  late  as  1947  after  which  filters  will 
be  required  at  the  Southwest  plant  also.  The  estimated  cost  of  con- 
structing all  plants  under  this  flow  is  $61,477,920  in  1935,  and  $67,- 
926,100  in  1945. 

The  annual  cost  of  operating  all  pumping  stations  and  disposal 
plants  is  estimated  at  $4,530,400  in  1935  and  $5,137,000  in  1945. 

16th.    Required  Works  with  8,500  Cubic  Feet  Per  Second  Flow: 

The  required  works  with  8,500  cubic  feet  per  second  flow  would  be 
the  same  as  those  required  for  10,000  cubic  feet  per  second  flow.  The 
construction  and  operating  cost  would  be  the  same  as  those  outlined  un- 
der the  project  in  paragraph  above. 

17th.    Review  of  Expenditures  Under  Various  Diversions: 

The  expenditures  for  construction  and  operation  of  the  treatment 
works  required  for  1935  and  1945  conditions  with  flows  varying  from 
2,000  to  10,000  cubic  feet  per  second  are  shown  in  Table  1. 

Increasing  the  flow  from  4,167  to  10,000  cubic  feet  per  second 
saves  but  sixteen  and  one-half  percent  in  the  expenditures  required  for 
sewage  treatment,  and  but  fourteen  and  one-half  percent  in  the  annual 
operating  costs. 

18th.    Suggestion  for  Stockyards  Wastes: 

The  Sanitary  District  program  contemplates  a  separate  sprinkling 
filter  plant  at  Argo  and  a  separate  activated  sludge  plant  for  the  Stock- 
yards wastes.  Other  cities  in  which  the  packinghouse  waste  per  capita 
contributing  sewage  is  as  great  as  that  at  Chicago  have  found  it  practi- 
cable to  treat  this  waste,  mixed  with  the  domestic  sewage,  at  either 
sprinkling  filter  or  activated  sludge  plants.  At  Chicago  the  Southwest 
Side  intercepter  passes  almost  directly  by  the  Stockyards,  which  sug- 
gests the  further  practicability  of  combining  this  concentrated  waste, 
after  the  removal  of  the  coarse  solids,  with  the  domestic  sewage  before 
treatment. 

If  treatment  of  the  Stockyards  waste,  mixed  with  the  sewage  of 
the  West  and  Southwest  Side,  is  practicable  on  stone  filters,  there  will 
result  a  saving  in  construction  cost  of  from  $2,300,000  to  $3,500,000. 
There  will  also  result  a  saving  in  annual  cost  of  operation  of  $350,000 
per  year,  even  after  crediting  an  income  of  $360,000  per  year  from  the 
sale  of  the  sludge  from  the  activated  sludge  plant.  This  annual  saving 
capitalized  at  four  percent  adds  a  further  sum  of  $8,500,000,  making  the  ^ 
total  capitalized  saving  between  $10,800,000  and  $12,000,000. 

The  rates  of  flow  for  dilution  purposes,  as  stated  in  this  report,  are 
the  estimated  rates  required  under  warm  weather  conditions  at  which 


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time  the  rate  of  diversion  would  necessarily  be  greatest.  It  is  a  fact 
that  considerably  smaller  rates  of  diversion  will  be  required  in  the  cooler 
months  of  the  year.  Riparian  owners  on  the  Great  Lakes  and  other 
parties  interested  are  chiefly  concerned  with  the  average  yearly  diver- 
sion. It  is  believed  to  be  proper  therefore  in  the  operation  of  the  Drain- 
age Canal  to  vary  the  draft  of  diversion  water  from  month  to  month 
dependent  upon  conditions.  The  ability  to  do  this  will  provide  a  large 
factor  of  safety  for  maintaining  good  conditions  in  the  efiluent  channels 
and  down-stream  rivers. 

We  have  made  no  allowance  for  the  fact  that  more  or  less  sewage 
from  the  Indiana-Calumet  region  now  containing  180,000  people,  now 
reaches  the  Sag  Canal  in  a  more  or  less  unpurified  state.  This  situation 
must  ultimately  be  solved  by  adequate  purification  works  for  this  region, 
and  a  specific  allowance  for  dilution  water  if  the  sewage  continues  to 
flow  via  the  Illinois  River. 

The  conclusions  in  this  report  are  predicated  on  keeping  the  Drain- 
age Canal  reasonably  clean  of  organic  settlings  by  dredging.  Very 
little  will  be  required  in  this  regard  after  purification  works  are  built, 
and  after  the  present  deposits  are  removed.  Several  years  may  be  re- 
quired before  existing  sludge  deposits  in  the  Illinois  River  are  com- 
pletely eliminated. 

We  have  given  no  consideration  to  the  development  of  water 
power.  We  have  neither  included  the  costs  thereof,  nor  credited  bene- 
fits. Where  power  is  required  in  the  operations  of  pumping  and  sewage 
disposal  we  have  estimated  the  cost  thereof  on  the  basis  of  electric 
power  purchased  from  the  Commonwealth  Edison  Company  at  their 
published  rates. 

Upon  the  pages  which  follow  we  have  discussed  the  matters  above 
treated  in  further  detail. 


12 


PART  II. 

PRESENT  DISPOSAL  OF  SEWAGE  AND  DEFICIENCIES 

Chicago,  and  the  industrial  region  surrounding  it,  occupies  the 
Southwestern  shore  of  Lake  Michigan.  The  ground  is  comparatively 
low.  The  greater  part  of  it  Hes  less  than  20  feet  above  Lake  Michigan. 
This  entire  region  formerly  drained  naturally  into  the  lake  through  the 
Chicago  and  Calumet  Rivers.  That  locality  now  constituting  the  west- 
ern suburban  area,  however,  is  tributary  to  the  Des  Plaines  River,  which 
parallels  the  lake  shore  about  ten  miles  inland,  the  waters  of  which  are 
tributary  to  the  Mississippi  river  system  through  the  Illinois  river. 

More  than  three  milHon  people  now  occupy  this  territory.  It  is 
conservatively  estimated  that  the  population  will  double  within  the  next 
thirty  years.  The  present  flow  of  sewage  is  about  800  million  gallons 
per  day.  This  is  equivalent  to  a  river  100  feet  wide  and  five  feet  deep 
flowing  one  and  one-half  miles  per  hour. 

The  shore  line  of  Lake  Michigan  from  Gary  on  the  south  to  Wau- 
kegan  upon  the  north  is  about  seventy-five  (75)  miles  in  length.  More 
than  half  of  it  is  densely  populated.  Much  of  it  is  occupied  by  industries. 
The  northern  one-third  of  it  is  residential  in  character. 

Development  of  Sewers. 

Sewers  were  built  as  required,  draining  immediately  to  the  nearest 
water  outlet.  The  earliest  settlement  of  considerable  size,  was  located 
at  the  mouth  of  the  Chicago  river.  In  this  locality  all  sewers  drain 
directly  into  the  river  or  into  its  north  or  south  branch.  As  the  popula- 
tion extended  northward  and  southward,  sewers  were  built  discharging 
directly  into  the  Lake.  When  sewers  became  necessary  in  the  region 
adjoining  the  Calumet  River,  sewers  were  built  discharging  directly  into 
this  stream. 

The  construction  of  sewers  in  Chicago  was  begun  in  1856.  At  this 
time  the  population  was  about  80,000.  Thereafter  the  growth  of  the 
city  was  very  rapid.  The  mileage  of  sewers  kept  pace  with  the  popula- 
tion for  in  many  localities  the  habitation  was  not  practicable  until  sewers 
had  been  built. 

Early  Disposal  of  Sewage. 

Sewers  discharging  into  the  Chicago  River  and  branches  ultimately 
reached  the  lake  except  for  a  small  amount,  which  from  the  earliest  use 


13 


of  sewers,  reached  the  old  IlHnois  and  Michigan  canal  by  pumping,  and 
thus  passed  to  the  Des  Plaines  and  Illinois  Rivers. 

Illinois  and  Michigan  Canal. 

The  Illinois  and  Michigan  canal  was  completed  in  1848.  It  paral- 
lels the  Drainage  Canal  a  few  hundred  feet  to  the  south.  Its  water  sup- 
ply was  obtained  partly  by  gravity  from  the  Calumet  River  and  partly 
by  water  pumped  from  the  south  branch  of  the  Chicago  River.  From 
time  to  time  the  pumping  works  were  increased  in  capacity,  which  tem- 
porarily tended  to  improve  the  foul  conditions  in  the  Chicago  River,  and 
to  divert  some  of  the  sewage  from  the  lake. 

Water  Supply. 

The  water  supply  for  the  City  of  Chicago  and  for  all  its  suburbs 
bordering  the  lake  is  taken  from  Lake  Michigan.  Public  Water  Works 
for  Chicago  began  operation  in  1856.  Water  was  taken  from  the  lake  at 
the  foot  of  Chicago  Avenue,  about  one  mile  north  of  the  mouth  of  the 
Chicago  River.  As  the  occupied  area  of  the  city  grew  it  became  neces- 
sary to  construct  additional  Water  Works'  intakes,  and  as  the  pollution 
from  the  sewers  was  constantly  increasing,  the  intake  cribs  were  pro- 
gressively located  farther  from  the  shore. 

At  the  present  time  the  city  is  supplied  through  six  cribs  varying 
from  two  to  four  miles  distant  from  the  shore  line. 

In  the  years  of  rapid  municipal  growth  up  to  1890,  the  sanitary 
conditions  in  the  outlet  streams,  particularly  the  Chicago  River  and  its 
branches,  became  progressively  worse.  Comparatively  great  accumula- 
tions of  filth  were  washed  into  the  lake,  and  occasionally  reached  the 
Water  Works'  intakes.  This  resulted  in  the  general  prevalence  of 
typhoid  fever,  and  occasional  epidemics. 

Drainage  Canal. 

We  will  not  recite  here  all  the  steps  that  were  taken  to  bring  about 
an  improvement  in  the  sanitary  conditions.  These  matters,  while  of 
general  interest,  are  recited  elsewhere,  and  bear  only  indirectly  upon 
this  problem.  The  most  important  step  taken  toward  improving  condi- 
tions was  the  passage  of  the  State  law  creating  the  Sanitary  District  of 
Chicago  and  empowering  it  to  construct  the  Chicago  Sanitary  Ship 
Canal,  May  29th,  1889. 

The  Drainage  Canal  is  twenty-eight  miles  long  from  the  Chicago 
River  at  Robey  Street  to  the  Controlling  Works  at  Lockport.  It  creates 
a  reversal  of  the  flow  of  the  Chicago  River,  and  in  addition  it  draws  in 
certain  quantities  of  water  from  Lake  Michigan,  depending  upon  its 
controlled  rate  of  flow.   The  flow  is  controlled  at  the  foot  of  the  Canal. 


14 


This  work  was  started  in  1892  and  completed  January  2,  1900.  The 
flow  capacity  of  the  main  channel  is  approximately  10,000  cubic  feet  per 
second. 

In  1907  the  canal  was  extended  beyond  Lockport,  a  distance  of 
about  four  miles  to  concentrate  an  available  fall  of  about  thirty-four 
feet,  and  utilize  the  same  in  the  development  of  a  water  power  in  drop- 
ping the  canal  flow  down  to  the  level  of  the  Des  Plaines  River.  Since 
the  completion  of  this  power  plant  it  has  generally  formed  the  means  for 
regulating  the  flow  of  the  Drainage  Canal,  although  the  flow  can  also  be 
regulated  at  the  Controlling  Works,  four  miles  upstream. 

In  connection  with  the  utilization  of  the  main  drainage  canal  it  was 
necessary  to  improve  the  Chicago  River  in  order  to  permit  the  desired 
flow  without  interfering  with  navigation.  The  river  was  widened  and 
deepened  at  various  places  between  the  years  1897  and  1920.  In  1910 
the  north  shore  channel  was  completed  connecting  the  north  branch  of 
the  Chicago  River  with  Lake  Michigan  at  Wilmette.  At  this  place  a 
pumping  station  was  built  operating  at  about  three  feet  head.  This 
canal  and  pumping  station  serves  the  purpose  of  pumping  fresh  water 
into  the  head  of  the  north  branch  of  the  Chicago  River,  thus  improving 
the  sanitary  conditions  therein,  resulting  from  the  large  amount  of  sew- 
age received.  This  channel  is  eight  miles  in  length  and  has  a  capacity 
of  1,000  cubic  feet  per  second. 

The  Calumet  Sag  channel  taps  the  little  Calumet  River  at  Blue 
Island  diverting  the  water  thereof  westerly  and  joining  the  main  drain- 
age canal  at  Sag.  This  canal  was  completed  in  1922.  It  has  a  length  of 
sixteen  miles  and  a  capacity  of  2,000  second  feet. 

Intercepting  Sewers. 

With  the  opening  of  the  Drainage  Canal  January  2,  1900,  all 
sewage  discharging  into  the  Chicago  River  and  branches  was  diverted 
to  the  Illinois  River.  There  remained,  however,  a  considerable  amount 
of  sewage  which  reached  the  lake,  through  the  sewers  discharging  di- 
rectly therein.  To  stop  this  pollution  a  system  of  intercepting  sewers 
along  the  lake  shore  was  planned  and  built  by  the  City  of  Chicago. 

All  sewage  entering  the  lake,  between  the  Chicago  River  on  the 
north  and  87th  St.  on  the  south,  is  now  intercepted  by  a  main  sewer  on 
■  Stony  Island  Avenue  running  north  from  83rd  St.  and  thence  following 
Cornell  Avenue  and  the  shore  of  Lake  Michigan  to  39th  St.  At  this 
place  the  39th  St.  pumping  station  lifts  the  sewage  to  the  twenty  feet 
sewer  running  west  on  39th  St.,  entering  the  south  branch  of  the  Chi- 
cago River.  This  station  is  also  equipped  with  pumps  to  take  dilution 
water  directly  from  the  lake  for  the  purpose  of  keeping  the  south  fork 
of  the  river  clean.    Plans  are  now  under  yvay  to  extend  the  39th  St. 


Figure  1.— Map  of  the  Sanitary  District  at  Chicago  and  irtelnltar. 


15 


sewer  so  that  it  will  enter  the  drainage  canal  at  Western  Avenue  near 
31st  St.  This  will  obviate  the  necessity  for  dilution  water  in  the  south 
branch  of  the  river.  The  southern  part  of  the  Stony  Island  Avenue 
district  is  pumped  into  the  Stony  Island  Avenue  sewer  by  pumping 
station  constructed  and  operated  by  the  City  of  Chicago  at  73rd  St.  and 
Stony  Island  Avenue. 

The  South  Side  intercepting  sewer  was  completed  in  1907. 

The  North  Side  sewers  entering  the  lake  were  intercepted  by  the 
construction  of  sewers  paralleling  the  lake  shore  running  north  to  Law- 
rence Avenue,  and  from  Howard  Avenue  running  south  to  Lawrence 
Avenue.  At  Lawrence  and  Racine  Avenue  a  pumping  station  was  con- 
structed, discharging  the  sewage  westward  into  the  north  branch  of  the 
Chicago  River.  This  station  is  also  equipped  with  pumps  to  draw  dilu- 
tion water  from  Lake  Michigan  for  the  purpose  of  improving  the  char- 
acter of  the  water  in  the  north  branch  of  the  Chicago  River. 

A  similar  system  of  intercepting  sewers  north  of  Howard  Avenue 
lead  to  the  Evanston  pumping  station  at  Orrington  Avenue  and  Lake 
Street,  which  intercepts  the  remainder  of  the  lakeward  flowing  sewers 
south  of  Wilmette  and  discharges  the  sewage  into  the  north  shore 
channel. 

All  sewage  originating  in  the  Sanitary  District  north  of  Wilmette 
is  intercepted  by  a  system  of  sewers  terminating  at  the  north  shore 
channel  and  Sheridan  Road.  The  Wilmette  pumping  station,  located 
at  this  point,  is  equipped  with  pumps  to  draw  dilution  water  from  the 
lake  for  the  purpose  of  maintaining  cleanly  conditions  in  the  north 
shore  channel  and  the  north  branch  of  the  Chicago  River. 

The  North  Side  intercepters,  within  the  City  of  Chicago,  became 
effective  in  1908.  The  intercepting  sewer  system  north  of  Wilmette 
became  fully  effective  in  1916.  The  Evanston  sewer  and  pumping 
station  was  completed  in  1921. 

Calumet  Region. 

Sewage  within  the  City  of  Chicago,  south  of  87th  Street,  has  here- 
tofore been  discharged  directly  into  the  Calumet  River,  and  considerable 
of  it  still  reaches  the  river.  This  will  very  shortly  be  corrected  by  the 
completion  of  the  Calumet  intercepting  sewer  and  the  pumping  station 
at  95th  Street  and  the  Calumet  pumping  station  at  Indiana  Avenue  and 
125th  St.  With  the  completion  of  these  sewers  all  sewage  south  of  87th 
St.  will  be  pumped  into  the  Calumet  Sag  Channel  after  treatment,  and 
delivered  to  the  Chicago  Drainage  Canal  at  Sag. 

The  Sag  Canal  does  not  reverse  the  Calumet  River  system  at  all 
times,  the  flood  flow  of  this  stream  greatly  exceeding  the  capacity  of 


16 


the  Sag  Canal.  Periodic  discharges  from  the  Calumet  River  have  been 
a  serious  menace  to  the  water  supplies,  particularly  those  near  the 
mouth  of  the  Calumet.  This  menace  will  continue  to  a  greater  or  less 
extent. 


TABLE 

2. 

FLOW  IN  MAIN 

CHANNEL. 

Authorized  Flow 

♦Actual  Flow 

by  State  Law 

V_/U..  H  L.  jJtJl  Oct/. 

Year 

X^OpUldllOIl 

r  I.  per  oec. 

as  Corrected. 

1900 

1,640,000 

5,467 

2,990 

1901 

1,688,000 

5,627 

4,046 

1902 

1,736,000 

5,787 

4,302 

1903 

1,934',000 

6,447 

4,971 

1904 

1,985,000 

6,617 

4,793 

1905 

2,035,000 

6,783 

4,480 

1906 

2,090,000 

6,967 

4,473 

1907 

2,144',000 

7,147 

5,116 

1908 

2,195,000 

7,317 

6,443 

1909 

2^250^000 

7^500 

6,495 

1910 

2,308,000 

7,693 

6,833 

1911 

2,370,000 

7,900 

6,896 

1912 

2,432,000 

8,107 

6,938 

1913 

2,509,000 

8,363 

7,839 

1914 

2,589,000 

8,630 

7,815 

lyio 

2,652,000 

8,840 

1  790 

I,  too 

1916 

2,716,000 

9,053 

8,200 

1917 

2,782,000 

9,273 

8,726 

1918 

2,846,000 

9,487 

8,826 

1919 

2,916,000 

9,720 

8,595 

1920 

2,986,000 

9,953 

8,346 

1921 

3,063,000 

10,210 

8,355 

1922 

3,143,000 

10,477 

8,858 

1923 

3,214,000 

10,713 

8,348 

1924 

3,284,000 

10,947 

9,465 

*These  quantities  have  been  computed  from  the  latest  available  data. 
Note — From  Report  of  Engineering  Board  of  Review, 

Diluting  Water. 

It  was  the  original  idea  in  the  construction  of  the  Drainage  Canal 
that  the  sewage  of  the  Sanitary  District  would  be  diluted  by  mixing 
with  a  sufficient  amount  of  fresh  water  from  Lake  Michigan  to  render 
the  mixture  innocuous,  and  to  assist  in  the  natural  purification  of  the 
sewage  in  its  transit  through  the  Drainage  Canal  and  the  river  system 


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1900  1901 


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Figure  2. — Hydrograph  for  Chicago  Drainage  Canal  and  Illinois  River  at  Peoria,  1I00>19S4. 

Flow  of  Illinois  River  as  reported  bv  U.  S.  O.  S.  except  year  1900,  which  is  estimate  by  J.  A.  Harman. 


17 


below  same. 

Table  2  shows  the  average  flow  at  the  outlet  of  the  Drainage  Canal 
for  each  year  since  the  canal  was  opened  in  1900.  This  flow  was  limited 
in  the  early  years  by  the  ability  to  get  the  water  through  the  Chicago 
River.  Within  the  past  ten  years  the  flows  have  been  more  nearly  up 
to  the  pollution  requirements  of  the  population  served,  but  they  have 
never  been  adequate  to  properly  care  for  the  sewage  and  trade  wastes. 
The  table  also  shows  the  estimated  amounts  of  flow  required  by  the 
State  law  creating  the  Sanitary  District,  under  which  a  minimum  dilu- 
tion of  three  and  one-third  second  feet  per  thousand  people  was  re- 
quired. 

The  above  flows  include  the  sewage,  as  well  as  the  diversion,  for 
dilution  purposes.  Water  for  both  purposes  is  taken  from  the  lake. 
The  present  Hquid  volume  of  the  Chicago  sewage  is  approximately  1200 
second  feet  or  about  twelve  percent  of  a  total  diversion  of  10,000  second 
feet. 

Additional  Dilution. 

Immediately  after  passing  the  controlling  works  at  Lockport  the 
Drainage  Canal  water  joins  the  natural  flow  of  the  Des  Plaines  River. 
The  flow  of  this  stream  during  the  late  summer  and  fall  is  usually  negli- 
gible. Large  flows  of  fresh  water  are,  however,  brought  in  during  the 
flood  seasons. 

Below  Joliet  the  principal  tributary  is  the  Kankakee  River,  which 
joins  the  Des  Plaines  forming  the  Illinois  River.  The  next  principal 
tributary  is  the  Fox. 

The  net  effect  of  all  these  streams  and  other  minor  tributaries  com- 
ing in  above  Peoria  is  indicated  on  Figure  2,  which  shows  graphically 
the  flow  of  the  Illinois  River  at  Peoria,  and  the  flow  of  the  Chicago 
Drailiage  Canal  since  the  latter  was  opened  in  1900,  During  the  past  ten 
years  the  flow  of  the  Drainage  Canal  at  Lockport  has  generally  ranged 
between  8,000  and  9,000  second  feet.  During  the  two  dryest  months  in 
the  year  the  additional  flow  coming  in  above  Peoria  has  usually  ranged 
between  ten  and  twenty  per  cent  of  the  Drainage  Canal  flow.  During  the 
remainder  of  the  typical  year  this  additional  inflow  has  been  consider- 
ably more,  possibly  averaging  as  much  as  a  fifty  percent  addition  of 
fresh  Avater.  During  several  months  of  nearly  every  year  the  additional 
water  coming  in  has  been  fully  equal  to  the  flow  of  the  Drainage  Canal. 
In  certain  months  of  heavy  flow  it  has  been  four  to  five  times  as  great 
as  the  Drainage  Canal  flow.  During  the  year  1924,  which  was  a  year 
of  sustained  natural  flow  in  the  Illinois  river,  the  tributaries  above 
Peoria  brought  in  a  flow  of  fresh  water  fully  equal  to  the  Drainage 
Canal  flow  throughout  the  year  up  to  and  including  September. 


18 


Sewage  Treatment  Works. 

Realizing  the  inadequacy  of  dilution  as  a  permanent  solution  for  the 
Chicago  sewage  problem,  the  Sanitary  District  some  years  ago  began 
experimentation  and  the  preparation  of  plans  for  sewage  disposal  works 
to  supplement  the  dilution  project.  Up  to  the  present  time  treatment 
works  have  been  built  as  follows : 

Des  Plaines  River  Treatment  Plant. 

The  Des  Plaines  plant  is  located  at  Roosevelt  Road  and  S.  1st 
Avenue,  Maywood. 

At  this  place  a  system  of  intercepting  sewers  terminates,  draining 
an  area  of  18.5  square  miles  between  North  Avenue  and  22d  St.,  and 
west  of  Harlem  Avenue.  The  present  population  served  is  approxi- 
mately 39,000.  This  plant  serves  the  towns  of  Maywood,  Melrose  Park, 
Forest  Park,  River  Forest,  the  north  part  of  Oak  Park,  and  the  U.  S. 
Government  Speedway  Hospital. 

This  plant  began  operation  in  August,  1922.  It  consists  of  a 
pumping  plant,  an  electric  driven  power  plant  and  treatment  works  by 
the  activated  sludge  process,  including  a  dewatering  plant  for  sludge. 
The  capacity  of  the  plant  is  four  million  gallons  per  day ;  slightly  less 
than  this  amount  of  sewage  is  being  treated  at  present. 

This  plant  has  been  designed  with  the  view  to  experimentation  in 
order  more  effectively  to  plan  the  larger  plants  subsequently  to  be 
built. 

Calumet  Treatment  Works. 

The  Calumet  Treatment  Works  is  located  near  E.  125th  St.  ad- 
joining the  west  shore  of  Lake  Calumet.  It  is  intended  to  serve  all  the 
territory  south  of  87th  St.  Sewage  will  be  delivered  by  the  Calumet 
pumping  station.  Purified  effluent  will  be  discharged  into  the  Calumet 
Sag  Channel.  The  area  to  be  served  is  approximately  42.5  square  miles. 
It  has  a  present  population  of  179,000  of  which  approximately  100,000 
reaches  the  plant  at  present. 

The  plant  consists  of  a  system  of  Imhoff  tanks  having  an  estimated 
daily  capacity  of  55  M.  G.  D.  The  plant  was  put  in  operation  in  Sep- 
tember, 1922.  A  small  activated  sludge  plant  and  a  small  trickling  filter 
are  also  in  operation  at  this  site  for  experimental  purposes. 

Other  Works. 

The  Sanitary  District  includes  forty-nine  incorporated  cities  and 
villages,  many  of  which  are  so  located  as  to  make  it  economical  to  solve 
their  problems  separately. 


19 


Figure  3. — Map  of  the  Sanitary  District  of  Chicago  showing  sewage 
treatment  projects  and  intercepting  sewers. 
(Scale  appox.  1  inch  =  6  miles.) 


20 


The  District  has  built,  and  is  operating  a  small  settling  tank  and 
trickling  filter  plant  at  Morton  Grove,  completed  in  1914,  serving  J200 
people.   A  small  plant  has  also  been  completed  at  Glenn  View. 

Minor  treatment  projects  are  proposed  for  the  towns  of  LaGrange, 
Brookfield,  LaGrange  Park,  North  Brook,  Oak  Forest,  Posen  Robins, 
Upper  Des  Plaines  Towns,  Harvey  and  Schiller  Park.  Other  miscel- 
laneous plants  will  ultimately  be  required  for  outlying  towns. 

North  Side  Plant. 

Work  is  now  well  under  way  covering  the  North  side  sewage  treat- 
ment project  located  at  Howard  Avenue,  immediately  west  of  the  North 
Shore  Channel.  This  plant  will  consist  of  a  pumping  station,  an  electric 
driven  power  plant  and  an  activated  sludge  plant.  As  now  being  built 
it  will  have  a  capacity  of  175  M.  G.  D.,  and  it  will  be  subject  to  indefinite 
enlargement  by  the  addition  of  units.  Sludge  will  be  pumped  to  lagoon- 
ing  beds  southwest  of  the  city. 

The  disposal  tract  covers  188  acres.  The  project  serves  all  territory 
in  the  Sanitary  District  lying  north  of  Fullerton  Avenue.  Area  sixty- 
two  square  miles.  Present  population  (1927)  is  approximately  737,000. 
The  plant  is  scheduled  for  completion  in  1928. 

West  Side  Sewage  Treatment  Project. 

This  treatment  project  is  proposed  to  serve  an  area  of  57.5  square 
miles,  embracing  the  heart  of  Chicago,  and  lying  between  Fullerton 
Avenue  on  the  north  and  31st  St.  on  the  south,  and  extending  from 
Lake  Michigan  westward,  including  the  loop  district  of  the  city.  The 
population  at  the  present  time  is  about  1,340,000.  The  plant  will  be 
located  adjoining  the  north  bank  of  the  drainage  canal  somewhere  in  the 
vicinity  of  South  Harlem  Avenue.  Plans  for  this  plant  have  not  been 
made.  It  is  tentatively  proposed  to  use  sedimentation  tanks,  supple- 
mented by  sprinkling  filters  when  necessary. 

Southzvest  Side  Treatment  Works. 

A  similar  plan  is  proposed  for  the  Southwest  side  embracing  all 
remaining  territory  in  the  City  of  Chicago  north  of  87th  St.  and  south 
of  31st  St.,  lying  south  of  the  drainage  canal.  This  comprises  an  area 
of  59  square  miles.  The  population  at  present  is  about  910,000.  Some 
parts  of  the  district  are  sparsely  settled. 

Industrial  Wastes  Treatment  Projects. 

A  very  important  part  of  the  organic  load  contained  in  the  Chicago 
sewage  is  contributed  by  certain  industries,  particularly  the  packing 
industries  located  near  the  head  of  the  Drainage  Canal.    Also  the  Corn 


21 


Products  Company  located  at  Argo  on  the  Drainage  Canal  and  near 
the  western  city  limits. 

The  Packing  Town  wastes  and  the  Corn  Products  wastes  are  de- 
rived from  comparatively  small  areas  respectively.  The  wastes  are 
highly  concentrated  and  require  special  treatment.  Thoi:ough  studies 
have  been  made  in  cooperation  with  the  industries. 

Plans  have  been  made  to  treat  Packing  Town  wastes  by  the  acti- 
vated sludge  process. 

Further  experimentation  at  the  Corn  Products  plant  is  now  under- 
way. The  experiments  to  date  indicate  that  the  wastes  can  best  be 
treated  by  sprinkling  filters. 

Effectiveness  of  Disposal  Operations. 

The  diversion  of  the  sewage  from  Lake  Michigan  has  been  fol- 
lowed by  a  remarkable  reduction  in  typhoid  fever  in  the  City  of  Chicago. 
A  number  of  other  matters  have  contributed  to  this  improvement,  in- 
cluding the  chlorination  of  the  water  supply  which  was  begun  in  1912, 
the  pasteurization  of  milk  begun  in  1910,  and  also  no  doubt  other  im- 
portant causes  outside  of  the  Chicago  district,  which  have  been  instru- 
mental in  very  greatly  reducing  the  typhoid  death  rates  throughout  the 
United  States.    Table  3  shows  these  facts  in  tabular  form. 

Condition  of  the  Lake. 

Lake  Michigan  is  still  badly  polluted  in  the  Indiana  Calumet  region, 
from  the  Indiana  cities  and  the  periodic  discharge  of  sewage  from  the 
southern  part  of  Chicago,  a  part  of  which  still  reaches  the  Lake.  There 
have  also  been  periodic,  but  relatively  infrequent  sewage  discharges 
from  the  Chicago  river  due  to  flow  reversals  caused  by  floods.  Minor 
pollution  still  reaches  the  lake  from  the  suburban  towns  north  of  the 
Sanitary  District.  This  pollution  is  comparatively  small,  and  will  prob- 
ably become  less  with  improved  conditions  in  the  North  Shore  Sanitary 
District,  embracing  certain  suburban  towns  north  of  the  Cook  County 
line. 

Particularly  at  times  of  great  storms  the  sanitary  condition  of  the 
water  at  the  Chicago  intakes  is  very  bad.  This  subject  will  be  dis- 
cussed hereinafter. 

River  Conditions. 

During  recent  years  the  main  channel  of  the  Chicago  River  through 
the  heart  of  the  city,  while  not  seriously  objectionable,  nearly  always 
contains  evidence  of  floating  sewage.  Conditions  in  the  north  branch 
of  the  Chicago  River  generally  range  from  bad  to  fair,  depending  upon 
the  extent  of  operation  of  the  dilution  pumps.  The  south  branch  of  the 
river  to  the  head  of  the  Drainage  Canal  increases  in  foulness  as  the 


22 


additional  sewers  join  the  stream.  The  Drainage  Canal  throughout 
its  length,  as  would  be  expected,  always  bears  evidence  of  the  heavy 
sewage  load  carried.  Odors  on  the  banks  are  usually  noticeable,  but 
conditions  only  become  very  foul  during  the  summer  and  early  fall 
months. 

At  Lockport  dissolved  oxygen  is  normally  exhausted  during  the 
warm  weather  season.  A  similar  condition  prevails  generally  through- 
out the  Illinois  River  to  the  head  of  Peoria  lake  about  ninety-six  miles 

TABLE  3. 

ANNUAL  TYPHOID  FEVER   MORTALITIES   IN   CHICAGO  PER  100,000 

POPULATION. 

From  Report  of  Engineering  Board  of  Review,  and  Supplemented. 


Typhoid  Percent 

Fever  of  Total 

Years  Mortality  Mortality  Remarks 

1867  73.3  3.45 

1868  79.3  3.34 

1869  65.3  2.82 

1870  87.4  3.66 

1871  61.0  2.92 

1872  142.6  5.16 

1873  71.6  2.85 

1874  53.4  2.63 

1875  51.7  2.62 

1876  41.2  1.96 

1877  37.0  1.98 

1878  33.4  1.97 

1879  42.3  2.41 

1880  34.0  1.63 

1881  105.2  4.03 

1882  82.4  3.49 

1883  62.2  3.12 

1884  56.2  2.84 

1885  74.6  3.98 

1886  68.6  3.53 

1887  50.3  2.48 

1888  46.7  2.38 

1889  48.4  2.67 

1890  91.6  4.61 

1891  173.8  7.20 

1892  124.1  5.68 

1893  53.5  2.47 

1894  37.5  2.06 

1895  37.9  2.14 

1896  52.6  3.23 

1897  29.3  2.00 


23 


TABLE  NO.  3— Continued. 

J.  J'^XXUiU 

J?  C  V  cx 

KJL  X.  yj  Lctl 

Years 

Mortality 

Mortality  Remarks 

1898 

40.8 

2.79 

1899 

27.2 

1.73 

1900 

19.8 

1.35    Opening  of  Drainage  Canal 

1901 

29.1 

2.09 

1902 

44.5 

3.03 

1903 

31.8 

2.03 

1904 

19.6 

1.42 

1905 

16.9 

1.21 

1906 

18.5 

1.27    Opening  South  Side  Interceptors 

1907 

18.2 

1.16    Completion  South  Side  Interceptors 

1908 

15.8 

1.09    Opening  North  Side  Interceptors 

1909 

12.6 

0.87 

1910 

13.7 

0.90    Pasteurization  of  Milk 

1911 

10.7 

0.74    Completion  North  Shore  Interceptors 

1912 

7.6 

0.51    Chlorination  of  Water  Started 

1913 

10.6 

0.71 

1914 

6.9 

0.49 

1915 

5.3 

0.37 

1916 

5.1 

0.35 

1917 

1.6 

0.11    Complete  Chlorination  of  Water 

1918 

1.4 

0.08 

1919 

1.2 

0.09    Completion  Evanston  Interceptors 

1920 

1.1 

0.09 

1921 

1.1 

0.09    Completion  Calumet  Interceptors 

1922 

1.1 

0.10 

1923 

1.9 

0.16 

1924 

1.5 

0.13 

24 


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Figure  4.— Watershed  of  tbe  Illinois  Rirer  showing  drainage         of  main  stream  and  principal  tributaries. 


25 


below  Lockport.  Within  this  reach  of  the  streams  conditions  vary,  as 
to  the  presence  or  absence  of  oxygen  and  the  prevalence  of  putrefactive 
odors.  For  ten  years  or  more  the  natural  life  of  the  river,  animal  and 
vegetable,  has  been  destroyed.  No  life  is  present  except  sewage  organ- 
isms. The  water  is  not  suitable  for  bathing  and  is  disagreeable  for  users 
of  pleasure  craft. 

During  certain  seasons  objectionable  conditions  and  the  destruction 
of  the  natural  water  life  of  the  stream  has  occurred  as  far  south  as 
Peoria.  The  wet  season  of  1924  has  materially  improved  the  conditions 
in  Peoria  Lake. 

Conditions  in  the  Des  Plaines  and  Illinois  Rivers,  below  Lockport, 
have  been  aggravated  by  large  quantities  of  sewage  sludge  which  passes 
down  the  river  during  the  colder  months  of  the  year,  comparatively  in 
an  undecomposed  state,  which  tends  to  add  materially  to  the  demand  on 
the  oxygen  contained  in  the  water  during  the  summer  months,  when 
decomposition  reaches  a  maximum.  This  sewage  sludge  has  accumu- 
lated to  great  depths  behind  dams  and  in  other  places  where  the  current 
is  slack  during  the  twenty-five  years  that  the  Drainage  Canal  has  been 
operating.  Conditions  are  becoming  worse  with  the  increasing  organic 
load  discharged  by  the  Chicago  sewage  and  the  Chicago  industrial 
wastes. 

Incidentally  the  river  receives  additional  pollution  although  com- 
paratively of  small  amount  from  the  cities  between  Joliet  and  Peoria.  At 
Peoria  and  Pekin  important  additional  industrial  wastes  are  added  to 
the  river.  Up  to  the  present  time  this  pollution  has  been  small  as  com- 
pared to  the  Chicago  load. 

It  has  been  recognized,  by  all  concerned,  that  the  existing  condi- 
tions on  the  Illinois  River  should  not  be  permanently  tolerated.  For 
sometime  it  has  been  realized  that  unless  corrective  measures  are  ap- 
plied promptly,  these  conditions  will  become  materially  worse  with  the 
further  growth  of  the  Chicago  region. 

The  Chicago  sewage  problem  will  not  be  solved  until  the  water 
supply  of  the  Chicago  district  is  adequately  protected,  and  the  streams 
receiving  sewage  are  restored  to  a  condition  of  reasonable  cleanliness. 

Analytical  Studies. 

The  most  accurate  picture  of  the  sanitary  conditions  in  the  Des 
Plaines  and  Illinois  Rivers,  below  the  outlet  of  the  Chicago  Drainage 
Canal,  is  furnished  by  the  comprehensive  study  of  the  U.  S.  Public 
Health  Service,  covering  fourteen  months  beginning  July  1,  1921, 
and  ending  August  31,  1922.  A  complete  report  of  this  investigation 
has  not  yet  been  printed.  There  has  been  furnished  to  us,  however,  a 
series  of  tabulations,  summarizing  the  principal  results. 


26 


It  was  the  purpose  of  this  investigation  to  determine  the  extent  of 
pollution,  the  character  of  the  water  at  various  places  within  the  streams 
and  the  factors  that  particularly  affect  the  decomposition  of  the  organic 
matters  discharged  therein.  Twenty-seven  sampling  stations  were  es- 
tablished between  Lockport  and  the  mouth  of  the  Illinois  River.  Samples 
were  collected  daily,  or,  at  certain  points  tri-weekly,  from  mid-depth  of 
the  stream.  At  the  stations  between  Lockport  and  Shanahan,  the  latter 
place  just  above  the  mouth  of  the  Kankakee,  samples  were  collected 
from  the  center  of  the  stream.  At  all  stations  below  Shanahan  samples 
were  taken  at  three  points  from  the  cross  section.  Samples  were  care- 
fully taken,  iced  and  promptly  transported  to  the  nearest  laboratory. 
Examination  of  samples  was  made  in  all  cases  in  less  than  three  hours. 
The  average  time  was  much  shorter.  The  report  of  the  preliminary 
examination  states :  "Due  to  fluctuations  in  the  sewage  strength  from 
night  to  day  at  the  outlet  of  the  Sanitary  canal,  and  to  the  variation  in 
flow  caused  by  opening  and  closing  of  the  gates  at  the  power  plant  above 
Joliet,  it  is  probable  that  the  results  of  analyses  recorded  in  the  tables 
which  follow  do  not  represent  exactly  the  average  condition  throughout 
the  day  of  the  water  at  the  sampling  point." 

The  tabular  data,  accompanying  the  preliminary  report,  is  too  bulky 
to  present  in  full.  We  summarize  the  principal  features  of  it  on  Figures 
5  to  8  inclusive.  We  show  upon  these  diagrams  the  average  dissolved 
oxygen  for  each  month  during  the  investigation  at  each  of  the  sampling 
points.  Also  the  five  day  bio-chemical  oxygen  demand  for  the  same 
places  and  times.  These  determinations  represent  the  character  of  the 
water  from  the  pollution  and  nuisance  standpoints.  The  bio-chemical 
oxygen  demand  is  representative  of  the  amount  of  organic  pollution 
carried.  The  dissolved  oxygen  represents  the  possibility  of  local  nuis- 
ance and  the  practicability  of  existence  of  the  natural  water  life  of  the 
stream.  Both  determinations  considered  progressively  down-stream 
indicate  the  degree  of  improvement  in  the  sanitary  character  of  the 
water  flowing. 

Winter  Conditions. 

We  show  separate  diagrams  intended  to  indicate  typical  conditions 
in  the  four  seasons  of  the  year.  In  the  winter  time  the  dissolved  oxygen  - 
is  high  in  the  water  taken  from  the  lake  on  account  of  its  low  tempera- 
ture. It  will  be  observed  that  at  no  point  between  Lockport  and  the 
mouth  of  the  Illinois  does  the  dissolved  oxygen  fall  below  7.5  p.  p.  m. ; 
further  there  is  very  little  reduction  in  the  dissolved  oxygen  throughout 
the  travel  of  the  water  from.  Lockport  to  the  Mississippi.  The  net  total 
effect  is  an  increase. 


27 


The  organic  matter  (as  represented  by  5  day  b.  o.  d.)  is  very  high 
at  Lockport,  averaging  generally  from  twenty  to  twenty-four  p,  p.  m. 
Near  LaSalle  it  has  been  reduced  about  two-thirds  in  p.  p.  m.  and  about 
one-third  in  the  total  load  carried  by  the  stream,  allowing  for  the  addi- 
tional dilution  water  coming  in  from  the  tributary  streams  above 
LaSalle.  The  improvement  is  probably  due  largely  to  sedimentation 
supplemented  by  a  small  amount  of  oxidation.    Between  LaSalle  and 


28 


Peoria  the  improvement  is  much  greater  by  reason  of  further  sedimen- 
tation in  the  wider  and  deeper  river  between  LaSalle  and  Peoria.  The 
diagrams  plainly  show  the  additional  pollution  reaching  the  Illinois 
River  at  Peoria  and  Pekin,  and  the  improvement  of  the  stream  below 
Havana.  In  the  v/inter  season  there  is  apparently  practically  no  im- 
provement in  the  quality  of  the  sewage  and  dilution  water  between  Chi- 
cago and  Lockport.    At  this  season  of  the  year  each  sewer  drops  its 


cr    oo     f-  vx) 


29 


load  into  a  stream  of  ice  cold  lake  water.  Practically  speaking,  the 
sewage  travels  in  cold  storage  to  Lockport  and  throughout  its  course  to 
the  Mississippi  River.  Apparently  the  principal  improvement  in  the 
character  of  the  stream  is  due  to  sedimentation. 

Summer  Conditions. 

The  summer  conditions  present  a  very  different  picture.  At  this 
season  of  the  year  organic  decomposition  reaches  its  maximum,  produc- 
ing a  heavy  demand  on  the  oxygen  in  the  stream  with  a  tendency  to 
produce  putrefactive  conditions  with  attendant  odors  and  a  reduction  in 
the  oxygen  to  the  point  where  the  natural  water  life  of  the  stream  may 
be  suffocating. 

At  this  season  the  mixture  of  sewage  and  lake  water,  as  delivered 
at  Lockport,  has  an  organic  load  slightly  more  than  half  that  contained 
in  the  winter  season  (5  day  b.  o.  d.).  This  probably  results  from  oxi- 
dation and  septic  action  in  the  Drainage  Canal  above  Lockport,  the 


30 


result  of  the  decomposition  being  carried  away  partly  in  gases  and 
partly  in  inert  matter  carried  along  with  the  water  in  suspension.  At 
this  season  oxygen  is  practically  exhausted  in  the  Drainage  Canal  be- 
tween Chicago  city  limits  and  Lockport.  It  does  not  exceed  1  p.  p.  m. 
at  any  place  above  Chillicothe,  110  miles  below  Lockport.  Between 
Chillicothe  and  Peoria  the  stream  rapidly  recovers  its  oxygen  in  its 
traverse  through  Peoria  Lake.   This  is  due  to  the  reduction  in  organic 


31 


matter  that  has  taken  place  up-stream,  oxygen  absorption  from  the 
atmosphere  on  the  large  surface  of  Peoria  lake,  and  the  product  of 
oxygen-producing  aquatic  vegetation.  Below  Peoria  and  Pekin  there  is 
a  further  draft  upon  the  oxygen  resulting  from  added  pollution.  It  is 
considerably  reduced  at  the  mouth  of  the  Illinois.  From  Peoria  to  the 
mouth,  however,  the  Illinois  River  contains  sufficient  oxygen  to  permit 
a  thriving  natural  water  life.  The  reduction  in  the  organic  matter  (5 
day  b.  o.  d.)  is  somewhat  greater  than  in  the  winter  time,  taking  into 
consideration  the  comparatively  small  amount  of  diluting  water  coming 
in  from  the  natural  streams  below  Joliet.  The  organic  load  has  been  re- 
duced nearly  two-thirds  from  Lockport  to  Peoria.  It  suffers  a  large 
increase  at  Peoria  and  Pekin  and  is  again  reduced  in  traveling  to  the 
mouth  of  the  stream. 

As  would  be  expected,  from  the  absence  of  oxygen,  between  Lock- 
port  and  Chillicothe  the  river  is  in  a  very  foul  condition.  It  is  entirely 
devoid  of  natural  stream  life.  It  is  possible  for  sewage  organisms  only 
to  live  in  this  water.  Below  Chillicothe  the  rapid  increase  in  the  dis- 
solved oxygen  creates  a  very  different  condition.  Below  Peoria  in 
1921-22  conditions  probably  permitted  the  presence  of  fishes  of  all  kinds 
naturally  inhabiting  the  stream. 

Spring  and  Fall  Conditions. 

The  spring  and  fall  conditions  typify  the  transition  from  the  winter 
conditions  to  the  summer  conditions,  and  from  the  conditions  of  summer 
to  the  conditions  of  winter.  This  is  due  to  the  gradually  warming  water 
in  spring  as  summer  is  approached,  and  the  gradual  chilling  of  the  water 
between  September  and  November.  This  effect  is  plainly  evident  on 
Figures  6  and  8.  Each  diagram  carries  a  tabular  statement  of  flow  from 
Joliet  to  Peoria.  Attention  is  invited  to  the  month  of  April,  1922,  in 
which  the  flow  at  Peoria  was  nearly  five  times  the  flow  at  Joliet. 

The  effect  of  this  additional  dilution  water  is  evident  in  the  reduced 
organic  content  (5  day  b.  o.  d.)  at  Peoria.  Allowing  for  this  dilution 
the  total  organic  load  of  the  stream  at  Peoria  is  apparently  reduced  to 
fifty  percent  as  compared  to  the  vicinity  of  Lockport,  indicating  that 
the  agencies  of  oxidation  and  possibly  sedimentation  persist  in  floods. 

Past  Conditions — Illinois  and  Des  Plaines  Rivers. 

What  has  been  said  above  typifies  as  accurately  as  possible  condi- 
tions which  prevail  at  present.  These  conditions  have  been  progres- 
sively growing  worse  since  the  Drainage  Canal  began  to  operate  in  1900. 

The  following  is  quoted  from  a  recent  statement  of  Dr.  Stephen  A. 
Forbes,  Chief,  State  Natural  History  Survey  Division,  Illinois  Depart- 
ment of  Registration  and  Education : 


32 


"A  serious  and  practically  continuous  study  of  the  system  of  the  plant 
and  animal  life  of  the  Illinois  River  was  begun  by  the  State  Natural  History 
Survey  of  Illinois  in  1894  and  has  been  continued  with  only  one  important 
interruption  to  the  present  year.  The  actual  periods  of  active  field  operations 
on  the  river  were  as  follows:  1894-1899  inclusive,  1901-1903,  1909-1912, 
1913-1915,  1918,  1920,  and  1922-1924.  The  interval  of  five  years  after  1903  was 
given  mainly  to  the  preparation  and  publication  of  a  final  report  on  the 
fishes  of  the  State. 

"We  have  had  from  the  very  beginning  until  now  the  continuous  co- 
operation of  the  Water  Survey  of  the  State,  upon  which  we  have  depended 
for  chemical  tests  and  analyses,  and  for  bacterial  data. 

"Our  reason  for  so  prolonged  attention  to  a  single  subject  is  found  in  the 
progressive  changes  in  the  stream  itself,  its  content,  and  its  environment, 
which  have  worked  corresponding  changes  in  the  aspect  and  internal  order 
of  its  biology,  requiring  frequent  repetition  of  our  studies  and  a  consequent 
revision  of  our  conclusions.  The  most  important  of  these  changes  have  been 
the  introduction  of  the  European  carp  in  1885  and  its  enormous  multiplication 
until  it  has  become  more  abundant  than  all  the  other  fishes  of  the  stream 
taken  together;  a  general  diking  and  reclamation  of  the  very  extensive 
bottomlands  of  the  river  and  the  draining  of  their  numerous  lakes;  and  a 
rapidly  increasing  pollution  of  the  stream  by  sewage  wastes  from  towns  on 
its  banks,  and  especially  from  the  Sanitary  District  of  Chicago.  It  is  a  very 
difficult  matter  to  disentangle  these  several  causes  of  change  in  a  way  to 
distinguish  clearly  their  separate  biological  aspects.  There  was,  for  example, 
a  large  and  rapid  increase  in  the  fisheries  yield  of  the  river  at  about  the 
time  of  the  opening  of  the  sanitary  canal  in  1900,  sometimes  attributed  to 
the  canal  itself,  but  largely  due  to  a  rapid  multiplication  of  the  carp  before 
1900;  and  there  has  been  of  recent  years  a  general  falling  off  in  the  fisheries 
yield  coincident  with  increasing  pollution  of  the  stream,  but  this  is  in  great 
measure  consequent  upon  a  restriction  of  the  overflow  of  levees  and  the 
draining  of  the  lakes. 

"In  this  confusion  of  causes  and  effects,  it  is  quite  impossible  to  show 
clearly  and  fully  just  how  and  to  what  extent  the  remarkable  fisheries  yield 
of  the  river,  amounting  in  1908  in  prices  paid  to  fishermen,  to  a  dollar  for 
every  two  feet  of  its  length,  has  been  affected  by  sewage  pollution,  but 
I  must  do  what  I  can  to  this  end  in  the  brief  time  alloted. 

"The  injurious  biological  effects  of  pollution  of  the  Illinois  River  by  raw 
sewage  from  Chicago  have,  of  course,  varied  widely  according  to  a  number 
of  local  and  temporary  conditions.  Being  greatest  at  the  upper  end  of  the 
river  at  mid-summer  temperatures,  and  at  low  water,  and  increasing  with 
the  population  of  the  Sanitary  District  and  with  the  activity  of  operations 
at  the  Chicago  Stock  Yards,  they  have  diminished  downstream,  with  lower 
temperatures  of  the  advancing  season,  and  with  the  rise  of  the  river  levels. 
At  their  worst  they  have  destroyed  or  driven  from  the  upper  Illinois  all  its 
clean-water  plants  and  animals,  including,  of  course,  its  fishes,  substituting 
for  them  those  normal  to  septic  or  pollutional  conditions.  In  the  mid- 
summer of  1911  the  upper  ten  miles  of  the  river  were  practically  a  septic 
tank,  the  gases  of  the  bottom  sludges  being  79%  methane;  19%  carbon 
dioxide;  1.02%  nitrogen;  0.56%  carbon  monoxide;  0.03%  oxygen.  There 


33 


were  no  fishes  in  that  part  of  the  stream,  or  for  many  miles  below,  and  no 
moUusks  or  crawfishes  on  the  bottom,  the  only  animals  there  being  sludge 
worms,  certain  midge  larvae,  and  other  foul  water  forms  able  to  live  without 
oxygen  on  the  crude  sewage  precipitates.  From  this  extreme  condition 
there  was  a  gradual  shading  off  downstream  until  at  a  distance  of  sixty  to 
seventy  miles  from  the  point  of  entrance  of  Chicago  sewage  the  plant  and 
animal  life  of  the  stream  was  virtually  normal.  Seven  years  later,  however, 
that  is,  in  1918,  pollutional  conditions  had  moved  downward  some  60  miles 
farther,  the  river  being  at  this  time  nearly  deserted  by  fishes  as  far  as  the 
Peoria  lakes,  93  miles  down  the  stream,  characteristic  sewage  organisms 
having  extended  their  range  in  thrifty  condition  to  77  miles  from  its  origin, 
and  the  areas  of  offensive  pollution,  distinguished  by  a  stinking  sludge  con- 
taining an  abundance  of  sewage  worms  and  no  clean  water  organisms,  had 
moved  downstream  from  Ottawa  to  Lacon,  a  distance  of  51  miles, 

"An  expansion  of  the  river  17  miles  long  and  up  to  a  mile  in  width, 
known  as  Peoria  Lake,  (although  really  a  chain  of  three  lakes  connected  by 
so-called  narrows)  served  as  a  partial  barrier  to  a  further  extension  of  the 
conditions  of  the  upper  river  until  the  period  of  the  world  war  when,  coin- 
cident with  an  enormous  increase  in  the  organic  wastes  of  the  Chicago 
stockyards,  these  pollutional  conditions  were  still  further  extended  and 
intensified,  culminating  in  1920  in  a  virtual  extermination  of  the  original  life 
of  the  river  bottom  as  far  down  as  Peoria  Lake  and  in  the  lake  itself  and 
in  the  substitution  for  it  of  plants  and  animals  usually  to  be  found  only  in 
heavily  polluted  water. 

"With  the  close  of  the  war  and  a  diminished  outpouring  of  stockyards 
sewage,  there  has  been  a  noticeable  improvement  of  conditions  in  Peoria 
Lake,  although  in  1922  they  were  still  far  below  their  pre-war  status;  but  in 
this  year  1924,  which  has  been  characterized  by  an  extraordinary  high  water 
level  of  unexampled  long  continuance,  Chicago  sewage  has  been  so  far 
diluted  that  fishes  have  ascended  the  stream  to  LaSalle,  60  miles  above 
Peoria  and  only  50  miles  from  the  river  head, 

"There  seemed  at  one  time  to  be  good  general  ground  for  believing  that 
the  addition  of  household  sewage  to  a  stream  might  increase  its  fisheries 
yield,  especially  where,  as  in  the  Illinois  River,  this  addition  was  made 
far  enough  above  the  more  productive  fishing  grounds  to  permit  the  oxida- 
tion of  nitrogenous  materials  and  their  conversion  into  forms  available  as 
food  for  fishes  young  or  old,  but  our  more  recent  computations  show  that 
there  has  always  been  an  abundance  of  food  in  the  Illinois  River  for  a 
much  larger  stock  of  fishes  than  it  carried — that  the  food  supply,  in  other 
words,  has  not  been  the  limiting  factor  in  the  river  fishes,  and  that  an  in- 
crease of  it  consequently  could  not  be  a  benefit, 

"The  product  of  this  present  season's  operations  on  the  river  has  not 
yet  been  sufficiently  worked  up  to  give  us  more  than  fragments  of  the  biolo- 
gical picture,  but  one  feature  may  be  of  special  interest  to  sanitary  engineers. 
We  found  in  the  summer  of  1911  that  heavy  rains  at  a  given  point,  followed 
by  a  rise  in  the  river,  increased  the  organic  contents  of  the  water  and 
diminished  the  ratios  of  dissolved  oxygen,  the  latter  effect  being  continued 
downstream  as  putrefaction  increased,  so  that  oxygen  ratios  were  actually 
diminished  downwards  instead  of  increasing  as  they  usually  do;  and  this 


34 


effect  of  local  contamination  by  washing  rains  was  still  more  clearly  shown 
this  summer  by  bacterial  data  contributed  by  the  State  Water  Survey. 
Taking,  for  example,  two  points  below  Peoria  which  were  six  miles  apart 
with  a  tributary  stream  between  them;  on  July  31  the  water  at  the  upper- 
most of  these  points  averaged  8000  bacteria  to  the  c.  c.  and  that  at  the  lower 
point  32,000,  while  on  August  8,  soon  after  a  very  heavy  rain,  when  the 
upper  count  was  4,000  instead  of  the  former  8,000,  the  lower  count  was 
120,000  instead  of  the  former  32,000,  this  jump  in  numbers  being  evidently 
due  to  the  muds  swept  in  from  the  tributary  after  the  storm. 

"Time  fails  me  to  attempt  to  follow  the  effect  of  Chicago  pollution 
beyond  the  wide  water  of  Peoria  Lake,  where  the  situation  becomes  com- 
plicated, indeed,  by  a  heavy  addition  of  fresh  sewage  from  Peoria  itself  and 
from  the  city  of  Pekin,  9  miles  below,  and  it  is  certain  that  in  1920  this  lake 
barrier  was  being  forced  and  that  the  life  of  even  the  lowest  of  the  chain 
of  three  was  far  from  normal — that  the  lakes  were  delivering  to  the  river 
beyond  a  considerable  part  of  the  load  of  trouble  which  they  had  received 
from  above." 

It  is  impracticable  definitely  to  show  the  progressive  deterioration 
in  the  quality  of  the  water  in  the  Illinois  River  throughout  the  entire 
period  during  which  the  Drainage  Canal  has  been  contributing  flow, 
for  the  reason  that  during  this  period  of  twenty-five  years  the  technique 
of  water  analysis  has  changed  so  that  results  cannot  be  compared  numer- 
ically. No  such  comprehensive  studies  as  that  undertaken  by  the  U.  S. 
Public  Health  Service  have  been  made.  More  or  less  fragmentary 
studies,  however,  indicate  the  increasing  pollution  with  the  growth  of 
the  population  and  industries  in  Chicago. 

We  show  on  Figure  9  a  series  of  dissolved  oxygen  readings  made 
by  the  State  W ater  Survey  covering  six  round  trips  between  July  22nd 
and  September  11th,  1911,  a  single  trip  between  July  11th  and  July  13th, 
1912,  a  single  trip  between  August  28th  and  September  3rd,  1918,  and 
four  round  trips  between  July  15th  and  September  17th,  1920.  This  dia- 
gram indicates  that  in  1911  the  summer  oxygen  content  was  fairly  satis- 
factory up-stream  as  far  as  Marseilles.  In  1918  and  1920  the  conditions 
were  very  similar  to  those  typified  by  the  Public  Health  studies  as  far 
south  as  Chillicothe. 

Ice  Conditions. 

Although  the  conditions  on  the  Illinois  River  during  the  winter  are 
generally  favorable  as  regards  nuisance,  and  not  particularly  detrimental 
to  the  natural  life  of  the  stream,  yet  occasionally  protracted  cold 
weather  and  an  unusually  extensive  covering  of  ice  brings  about  unfa- 
vorable conditions  During  the  winter  of  1924  and  1925  this  unfavor- 
able condition  prevailed. 

An  investigation  under  the  direction  of  Dr.  Forbes  brought  out  the 
following  facts.  In  Clear  Lake,  below  Pekin,  the  dissolved  oxygen  con- 


35 


tent  of  the  water  varied  from  0.4  to  1.8  p.  p.  m.  All  kinds  of  fish  were 
found  to  be  dead  in  set  nets  and  also  under  the  ice  outside  of  the  nets. 
At  Quiver  Lake,  just  above  Havana,  where  the  water  contained  2.5 
p.  p.  m.  a  river  seine  hauled  under  the  ice  gave  carp,  buffalo  and  gars ; 


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36 


all  stupid,  pallid  in  color  and  of  a  disagreeable  odor  called  "gassy"  by 
fishermen,  characteristic  of  fish  taken  from  polluted  water.  At  Tread- 
way  Lake,  near  Meredosia,  where  the  oxygen  content  was  5.4  to  5.8^ 
practically  the  entire  variety  of  river  fish  were  being  taken  in  hoop  nets, 
all  in  good  condition. 

Similar  conditions  were  noted  by  the  State  Natural  History  Survey 
in  1912.  This  condition  unfavorable  to  fishes  is  brought  about  through 
organic  pollution  in  the  water,  coupled  with  the  inability  of  the  stream 
to  replenish  its  oxygen  supply  from  the  air.  That  these  conditions  are 
due  to  sewage  pollution  is  shown  by  recent  observations  of  Dr.  Forbes* 
department,  referring  to  Clear  Lake,  Quiver  Lake,  Coleman  and  Tread- 
way  Lakes.  Also  in  Quiver  Creek.  Clear  Lake  is  the  farthest  upstream 
and  contains  only  river  water  which  begins  to  enter  into  it  when  the 
river  is  three  and  one-half  or  four  feet  above  low  water  mark  at  Peoria. 
Conditions  there  were  as  previously  described.  Quiver  Lake  receives 
water  continually  from  the  river,  but  also  from  Quiver  Creek,  an  un- 
polluted stream.  Its  condition  is  consequently  not  so  deadly  as  that  of 
Clear  Lake,  although  the  mass  of  its  water  comes  from  the  river. 

Treadway  and  Coleman  Lakes  are  8  or  9  miles  above  Beardstown, 
on  the  same  side  of  the  river  and  a  little  distance  below  the  mouth  of 
the  Sangamon,  an  unpolluted  stream,  from  which  they  receive  a  large 
part  of  their  water. 

Investigations  in  the  above  lakes  show  a  gradation  from  practical 
complete  destruction  of  fish  under  the  ice  at  Clear  Lake,  most  open  to 
pollution,  to  normal  conditions  at  Coleman  and  Treadway  Lakes,  also 
frozen  over  but  filled  mainly  with  Sangamon  River  water.  The  Quiver 
Creek,  tributary  of  Quiver  Lake,  is  reported  to  have  shown  11.9  to  12.3 
of  oxygen,  and  to  have  yielded  in  hoop  nets  put  down  over  night  vigor- 
ous and  active  European  carp,  native  carp,  or  quill-back,  buffalo,  gars, 
channel  cat,  bullheads,  black  bass,  striped  bass  and  sheepshead,  a  good 
variety  of  ordinary  fish  in  good  condition. 

Thus  it  will  be  noted  that  the  fish  which  were  in  distress  were  oc- 
cupying polluted  waters,  and  were  apparently  not  affected  by  the  unpol- 
luted streams,  even  although  the  same  were  ice  bound. 

In  this  connection  it  should  be  noted,  however,  that  in  natural  lakes 
and  rivers,  unpolluted  by  sewage,  the  exhaustion  of  oxygen  and  the  dis- 
tress of  fishes  may  occur  under  the  ice  due  to  the  decomposition  of  vege- 
table organisms.  The  distress  of  fish  in  the  ice  bound  condition  of  the 
stream  was  observed  upon  the  Illinois  River  prior  to  1900.  This  situa- 
tion may  or  may  not  have  been  brought  about  by  sewage  contamination. 
While  the  stream  did  not  receive  a  large  pollution  from  Chicago  it  was 
rather  heavily  polluted  at  Peoria,  which  may  have  contributed  to  the  un- 


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37 


favorable  conditions  noted.  Relatively  speaking  the  river  as  a  whole 
was  an  unpolluted  stream  at  that  time. 

Future  Effect  of  Water-Way  Improvement. 

When  the  Illinois  water-way  is  built  some  changes  will  be  brought 
about  in  the  river  conditions,  principally  between  Lockport  and  LaSalle. 
In  this  reach  of  the  Des  Plaines  and  Illinois  Rivers  it  is  proposed  to  im- 
prove the  same  on  the  basis  of  slack  water  navig'ation.  To  accompHsh 
this  purpose  dams  will  be  constructed  at  Brandon  Road,  Dresden  Island, 
Marseilles  and  Starved  Rock.  The  pond  created  by  each  of  these  dams 
will  extend  to  the  foot  of  the  next  dam  up-stream. 

At  the  present  time  the  water  occupies  a  period  of  about  thirty- 
seven  hours  in  its  passage  from  Brandon  bridge  to  LaSalle.  Except 
for  the  pond  created  by  the  present  Marseilles  dam  the  current  is  rapid 
and  conditions  are  favorable  for  the  absorption  of  atmospheric  oxygen. 

After  the  construction  of  the  water-way  based  on  present  plans, 
contemplating  a  flow  of  about  10,000  second  feet,  the  time  of  travel  be- 
tween Joliet  and  LaSalle  will  be  increased  to  about  66  hours.  The 
water  surface  area  in  this  reach  of  the  stream  is  about  10.5  square  miles 
at  the  present  time.  The  dams  will  increase  it  to  about  thirteen  square 
miles. 

Below  LaSalle  the  flow  of  water  is  much  less  rapid.  Six  and  one- 
half  days  is  at  present  required  for  it  to  flow  from  LaSalle  to  Peoria. 
The  total  time  of  flow  from  Joliet  to  the  mouth  of  the  Illinois  River  is 
about  thirteen  days  at  summer  stages  with  present  flows. 

With  the  improved  water-way  assuming  a  flow  of  10,000  second 
feet  conditions  below  LaSalle  will  not  be  greatly  changed.  Proposed 
plans  contemplate  water  surface  elevations  which  differ  not  greatly  from 
those  prevailing  at  present.  With  this  flow,  however,  the  existing  dams 
will  probably  be  taken  out. 

Thus  the  net  result  of  the  construction  of  the  water-way  will  be 
practically  to  double  the  time  of  travel  from  Joliet  to  LaSalle,  and  to 
increase  the  area  of  water  surface  about  twenty-five  percent.  Below 
LaSalle  conditions  will  remain  about  as  at  present. 

Conditions  with  Smaller  Diversions. 

If  the  diversion  of  water  from  Lake  Michigan  is  very  much  below 
10,000  second  feet  the  plan  for  the  Illinois  water-way  will  probably 
require  the  retention  of  the  present  dams  below  LaSalle.  Above  La- 
Salle the  dams  contemplated  under  a  10,000  second  foot  flow  would 
probably  be  unchanged,  and  the  existing  areas  would  not  be  greatly  al- 
tered as  compared  to  the  larger  flow.    The  time  of  travel,  however. 


38 


would  be  increased  approximately  in  an  average  ratio  to  the  quantity  of 
water  flowing. 

Rough  approximations  of  the  time  of  travel,  assuming  various 
quantities  flowing  in  the  stream  would  be  as  follows : 


TIME  OF  TRAVEL  IN  DAYS. 

Joliet  LaSalle 

to  to  mouth  of 

LaSalle  Illinois  River 

10,000  feet  per  second                                              2.7  14.5 

8,500    "       "       "                                                     3.2  17 

7,500    "       "       "                                                     3.6  19 

4,167    "       "       "                                                     6.4  35 

2,000    "       "       "                                                   13  73 

It  is  believed  that  the  net  effect  of  the  construction  of  the  water- 
way will  be  to  introduce  into  the  Illinois  River  a  series  of  four  ponds 
above  LaSalle,  which  may  be  expected  to  have  a  similar  effect  to  that 
now  produced  in  Lake  Peoria.  It  is  believed  that  the  net  effect  upon 
the  stream  under  present  pollution  and  diversion  conditions  would  be  to 
throw  the  "dead  line"  now  existing  near  Peoria  Lake  much  further  up- 
stream. 


39 


PART  III 

POPULATION  AND  GROWTH. 

Chicago  has  grown  from  a  frontier  trading  post  to  the  third  city 
of  the  world  within  a  period  of  ninety  years.  It  is  the  commercial  and 
transportation  center  of  the  largest  and  richest  agricultural  community 
on  this  continent.  Its  position  is  such,  as  regards  lines  of  communica- 
tion, that  it  will  continue  to  be  the  hub  of  interior  America.  Its  future 
development  must  inevitably  follow  the  development  of  a  vast  interior 
region,  the  limits  of  growth  for  which  cannot  be  predicted. 

In  planning  sewage  disposal  works  for  this  great  industrial  center, 
it  obviously  will  be  wise  to  plan  for  a  larger  future  growth.  It  is  not 
financially  practicable,  however,  nor  is  it  wise  to  build  very  far  in  ad- 
vance of  immediate  requirements.  It  is  practicable,  however,  to  plan 
for  future  growth,  and  to  build  upon  a  unit  system  so  that  units  may  be 
built  a  little  in  advance  of  need.  If  the  plan  is  wisely  made  each  unit 
so  built  will  be  permanently  useful.  It  will  constitute  a  link  in  a  future 
chain  of  sev/age  disposal  works.  Thus  each  dollar  invested  will  be  a 
permanent  investment.  If  the  growth  is  more  rapid  than  anticipated, 
units  can  be  added  more  rapidly,  and  assessed  valuations  will  be  avail- 
able to  meet  the  necessary  charges.  If  growth  is  less  rapid  than  is  an- 
ticipated, works  constructed  from  year  to  year  will  be  useful  for  a  longer 
time. 

Population — Sanitary  District: 

The  Sanitary  District  of  Chicago  includes  fifty-two  towns  and 
villages  lying  within  Cook  County,  Illinois.  The  population  by  1920 
census  was  2,978,635,  of  which  2,701,705  or  ninety-one  percent  was  resi- 
dent within  the  corporate  limits  of  the  City  of  Chicago.  Table  5  is  a 
statement  of  the  population  within  the  present  boundaries  of  the  Sani- 
tary District  in  the  census  1900  to  1920  inclusive.  Within  this  period 
the  population  of  the  district  increased  sixty-seven  percent.  The  out- 
lying towns  and  villages  practically  trebled  in  population  during  the  two 
decades. 

Greater  Chicago  Region: 

Since  1900  municipal  growth  has  extended  beyond  the  Illinois  bor- 
der line  into  Northern  Indiana,  in  which  a  great  industrial  region  is 
developing,  served  by  numerous  main  lines  of  railroad  and  new  lake 


40 


harbors,  which  have  been  built  at  Gary  and  East  Chicago.  Improved 
labor  conditions  in  the  outlying  localities,  adjacent  to  Chicago,  have 
favored  the  location  of  certain  industries,  on  the  borders  of  the  city 
limits,  and  in  certain  cities  outside  of  Cook  County.  The  greater 
Chicago  region,  as  defined  by  U.  S.  census,  includes  Cook,  Kane,  Du- 
Page,  Lake  and  Will  Counties  in  Illinois  and  Lake  County  in  Indiana. 
The  total  population  of  this  region  was  3,521,789  in  1920.  It  had  in- 
creased seventy-five  percent  in  the  two  decades  following  1900.  Table 
6  shows  the  population  within  this  region  for  each  county  for  the  last 
three  census  years.  As  will  be  noted  the  Sanitary  District  of  Chicago 
includes  approximately  eighty-five  percent  of  the  total  population  of  the 
greater  Chicago  region. 

TABLE  5 

POPULATION  OF  CITIES  AND  VILLAGES  IN  THE  SANITARY  DISTRICT 

OF  CHICAGO 


Population 


Name 

1900 

1910 

1920 

943 

1,881 

5,841 

14,150 

6.114 

8,043 

11,424 

Brookfield  (village)   

1,111 

2,186 

3,589 

Burnham  (village)   

328 

795 

1,237 
2,701,705 

Chicago  (city)  

,  1,698,575 

2,185,283 

Cicero  (town)   

16,310 

14,557 

44,995 

DesPlaines  (village)   

1,666 

2,348 

3,451 

Dolton  (village)   

1,229 

1,869 

2,076 

Elm  wood  Park  (village)  

1,380 
37,234 

18,721 

25,668 

445 

424 

705 

4,085 

6,594 

10,768 

483 

683 

914 

1,020 

1,899 

3,381 

652 

760 

5,395 

7,227 

9,216 

127 

Hinsdale  (village)  (DuPage  County) . . . 

2,578 

2,451 

3,975 

336 

881 

1,188 

3,969 

5,282 

6,526 

730 

1,131 

1,684 

951 

1,483 

2,564 

4,532 

8,033 

12,072 

2,592 

4,806 

7,147 

564 

836 

1,079 

190 

276 

1,441 

514 

569 

1,258 

41 


eon 

ceo 

763 

Northbrook  (Schermerville)  (village).... 

CCA 

554 

3,447 

5,251 

6,897 

Oak  Park  (village)  

19,444 

39,858 

Park  Ridge  (city)  

1,340 

2,009 

3,383 

end 
679 

-1  rtoo 

l,9od 

0  AO 

94  < 

558 

917 

1,166 

River  Forest  (village)  

1,539 

2,456 

4,358 

River  Grove  (village)  

333 

418 

484 

Riverside  (inc.  N.  Riverside)  (village) . . . 

1,551 

1,702 

2,532 

Riverview  (village)   

406 

312 

334 

431 

390 

South  Holland  (portion  village)  

766 

1,065 

1,247 

Stickney  (village)   

550 

547 

949 

4,019 

359 

355 

Western  Springs  (village)  

662 

905 

1,258 

West  Hammond  (Calumet  City)  (city) . . . 

^,9o5 

4,948 

7,492 

2,300 

4,943 

7,814 

Winnetka  (village)   

1,833 

3,168 

6,694 

1,788,278 

2,338,278 

2,978,635 

Total  population,  excluding  Chicago. 

89,703 

152,995 

276,930 

TABLE 

6 

POPULATION  OF  THE  CHICAGO 

METROPOLITAN  DISTRICT 

1900 

1910 

1920 

County 

Census 

Census 

Census 

1,838,735 

2,405,233 

3,053,017 

78,792 

91,862 

99,499 

28,196 

33,432 

42,120 

34,504 

55,058 

74,285 

Will   

74,764 

84,371 

92,911 

37,892 

82,864 

159,957 

Total  

2,092,883 

2,752,820 

3,521,789 

Chicago  Growth  Compared  to  Other  Cities: 

We  show  on  Figure  11  a  diagrammatic  representation  of  the 
growth  of  Chicago  with  a  comparison  of  the  growth  of  London  and 
New  York,  the  only  cities  which  exceed  it  in  population ;  also  several 
other  cities.  It  will  be  observed  that  the  rate  of  growth  of  Chicago  has 
been  exceeded  only  by  that  of  New  York,  which  has  been  largely  in- 
fluenced by  annexations.  Figure  12  is  a  similar  diagram  showing  a 
little  more  clearly  the  growth  of  the  Chicago  region,  as  compared  to 


42 


London  and  New  York,  the  population  of  these  two  cities  being  platted 
for  the  several  decades  immediately  before  and  after  the  time  when  they 
passed  the  three  million  mark,  without  regard  to  the  year. 

Within  the  past  ten  years  there  have  been  several  comprehensive 
studies  of  the  future  growth  of  Chicago  and  vicinity ;  more  particularly 
the  studies  for  the  Chicago  Traction  Commission,  the  Commission  on 
Smoke  Abatement  and  also  several  studies  concerning  the  improvement 
of  the  Chicago  Water  Works.  The  Chicago  Telephone  Company  neces- 
sarily keeps  itself  quite  accurately  informed  as  to  the  probable  require- 
ments for  the  extension  of  its  service.  It  has  recently  made  a  study  of 
the  growth  of  the  Chicago  region. 


YtAR 

Figure  11. — Population  growth  of  Chicago  and  other  large  cities,  with  city- 
engineer's  forecast  for  the  city  of  Chicago. 


43 


All  these  investigations  substantiate,  with  reasonable  accuracy, 
the  figures  which  have  been  prepared  by  the  Sanitary  District  of  Chi- 
cago, as  representing  the  most  probable  future  population  of  the  Sani- 
tary District  so  far  as  it  can  be  determined  in  the  light  of  past  growth 
and  recent  development  in  this  region. 

Forecast  of  the  Sanitary  District: 

We  show  diagrammatically  on  Figure  12  the  forecast  of  the  Sani- 
tary District  for  the  population  within  the  Sanitary  District  up  to  the 
year  1970.   In  designing  sewage  purification  works  it  will  be  important 


iqoo        iqio         iq^o        is^o        iq4o        iq^o        isfco  iq7o 


(Do+cs  refer  +o  loco!  Popub-f  ion  onli^) 

1.  Chicago  oni_y,Teacxioni  Co.  FoeECAST 

2.  II  M        A-.SN.OF  COMfs^e.R.CE.  Sn/\0<H.  CoMM.'FoE.e.CAST 

Figure  12. — Population  growth  and  forecast  for  the  Sanitary  District  of 
Chicago  and  City  of  Chicago  in  comparison  with  growth  of  other 
large  cities.    (Dates  refer  to  local  population  only). 

1.  Chicago  only,  Traction  Co.  forecast. 

2.  Chicago  only,  Assn.  of  Commerce  Smoke  Comm.  forecast. 
*Note — Estimate  of  the  Sanitary  District  of  Chicago. 
Greater  London  population  3,000,000  in  1857. 

Greater  New  York  population  3,000,000  in  1895. 


44 


D  iaqram  Showinq 

Population  By  Districts 
Estimate  op 5anitarv  District 
of  chicago 

To  Accomporn^  R.cpor4-  o-P 
A\_VORD,  &URD\CX;8cH0W50M 


2.000,000 

l,cioo,ooo 

\.8oo,ooo 

l.'/oopoo 

1.600,000 

t,5oo,ooo 

1,4-00,000 

!. 300.000 

1.200,000 

l,!00,000 

1,000,000 
cfoo.ooo 
8do,ooo 
700.000 
€>oo,ooo 
5oo,ooo 
4oo,ooo 
3oo,ooo 
2oo,ooo 


NAo  iq5o 
Vear 


loo. 000 


iq-io 


Figure  13. — Population  by  districts.    Estimate  of  Sanitary  District 

of  Chicago. 


45 


to  determine  present  and  prospective  populations  by  locality,  as  a  basis 
for  determining-  the  amount  of  sewage  delivered  to  each  plant.  Table 
7.  shows  the  estimate  of  the  Sanitary  District  for  each  future  decade, 
divided  as  between  five  localities  in  which  purification  works  will  prob- 
ably be  required.  Figure  13  shows  the  same  facts  diagrammatically. 
This  diagram  is  chiefly  useful  in  illustrating  the  comparative  rates  of 
growth  in  the  different  parts  of  the  district,  and  in  preparing  approxi- 
mate estimates  of  population  for  the  years  intermediate  between  the 
census  years. 

TABLE  7 

PRESENT  AND   FUTURE    POPULATION   OF   AREAS   TRIBUTARY  TO 
TREATMENT  PLANTS,  AS  ESTIMATED  BY  THE  SANITARY 
DISTRICT  OF  CHICAGO 


Total 

North         West  all 

Year               Side            Side  Calumet  S.  W.  Side  Misc.  Plants 

1920                    590,000  1,300,000  160,000  850,000  100,000  3,000,000 

1930                    800,000  1,430,000  225,000  1,040,000  215,000  3,710,000 

1935                    915,000  1,490,000  255,000  1,135,000  275,000  .  4,070,000 

1940                  1,015,000  1,550,000  290,000  1,230,000  340,000  4,425,000 

1950                  1,230,000  1,680,000  350,000  1,415,000  465,000  5,140,000 

1960                 1,450,000  1,800,000  415,000  1,600,000  595,000  5,850,000 

1970                  1,670,000  1,920,000  480,000  1,780,000  730,000  6,580,000 


Distribution  of  Population: 

We  present  herewith  Figures  14  and  15  which  show  a  diagram- 
matic representation  of  the  distribution  of  the  population  of  Chicago  and 
vicinity  for  the  census  year  1920,  and  the  population  distribution  as  it 
will  probably  be  in  1940.  These  diagrams  were  prepared  by  the  Illi- 
nois Bell  Telephone  Company ;  each  spot  on  the  diagrams  represents 
100  families.  These  diagrams  serve  to  indicate  the  most  favorable  loca- 
tions for  sewage  purification  works.  As  will  be  pointed  out  later  the 
Sanitary  District  has  apparently  selected  the  most  favorable  sites  possi- 
ble for  purification  works,  in  that  localities  have  been  chosen  as  remote 
as  possible  from  present  and  future  habitation,  with  due  regard  to 
proximity  to  the  districts  contributing  sewage. 


Figure  H.— Map  of  Chicago  showing  distribution  of  population  in  1920. 


Figure  15. — Map  of  Chicago  showing  distribution  of  population  in  1940. 


48 


PART  IV 

AMOUNT  AND  QUALITY  OF  SEWAGE. 

In  a  study  of  the  sewage  problem  of  any  community,  a  knowledge 
of  the  volume  and  quality  of  the  sewage  is  of  primary  importance. 

With  respect  to  quality,  sewages  are  often  classified  as  domestic 
and  industrial,  and  the  use  of  these  terms  is  generally  intended  to  convey 
the  idea  that  domestic  sewage  is  that  resulting  from  strictly  domestic  or 
household  operations,  while  industrial  sewage  is  that  resulting  from 
manufacturing  or  industrial  operations. 

A  strictly  domestic  sewage  consists  of  the  water-borne  wastes  re- 
sulting from  household  operations  in  the  laundry,  kitchen,  bathroom, 
and  toilet  and  the  qualitative  character  of  such  wastes  is  substantially  the 
same  in  any  community  where  the  habits  of  life  of  the  people  do  not 
differ  materially.  Sewage  of  a  strictly  domestic  character  is  rarely 
encountered  in  large  cities,  as  most,  if  not  all,  of  our  large  cities  have 
more  or  less  varied  industries,  which  produce  waterborne  wastes  differ- 
ing in  quality  from  strictly  domestic  sewage.  The  character  and  extent 
of  industrial  operations  consequently  are  largely  responsible  for  any 
wide  differences  in  quality  which  may  be  found  in  the  sewages  of 
various  cities. 

Measurement  of  Load: 

Various  analytical  determinations  are  made  today  to  give  expres- 
sion to  the  quality  or  composition  of  sewage,  such  as  total  nitrogen,  free 
ammonia,  suspended  solids,  settleable  solids,  oxygen  absorbed  from 
permanganate,  stability  value,  biochemical  oxygen  demand,  etc.,  and  in 
the  discussion  of  the  quality  of  sewage,  the  only  analytical  value  which 
will  be  used  for  the  present  will  be  that  secured  by  the  biochemical  oxy- 
gen demand  test. 

The  biochemical  oxygen  demand  test  consists  of  incubating  a 
known  volume  of  sewage  with  known  volumes  of  pure  water  containing 
a  known  supply  of  oxygen  in  solution,  and  observing  the  rate  at  which 
the  oxygen  is  exhausted,  also,  the  total  amount  of  oxygen  required  to 
effect  a  complete  combustion  of  the  putrescible  matter  in  the  sewage. 
The  incubation  is  carried  out  at  a  constant  temperature,  usually  twenty 
degrees  C,  and  for  a  sufficient  number  of  days  to  accomplish  a  practic- 
ally complete  destruction  of  the  readily  oxidizable  material  in  the  sew- 


49 


age.  This  test  attempts  to  show  what  happens  in  the  way  of  oxygen 
depletion  in  a  stream  of  pure  water  when  it  is  polkited  with  sewage. 

It  has  long  been  known  that  streams  are  able  to  affect  a  destruction 
of  putrescible  matter  and  after  doing  so  to  recover  their  original  purity. 
When  sewage  is  discharged  into  a  stream  of  water  there  begins  a  drama 
with  three  actors,  namely  putrescible  matter,  bacteria  and  oxygen. 
Bacteria  and  oxygen  combine  to  destroy  putrescible  matter,  and  if  the 
bacteria  have  an  ample  supply  of  oxygen,  putrescible  matter  is  destroyed 
in  a  quiet  and  orderly  manner,  but  if  the  supply  of  oxygen  is  inadequate, 
the  drama  may  develop  into  a  tragedy,  and  although  the  bacteria  will 
eventually  triumph,  the  stream  will  suffer  considerably  from  the  exper- 
ience. 

The  problem  then  is  one  of  oxygen  supply,  if  sewage  destruction  is 
to  be  accomplished  without  offense,  and  there  are  a  number  of  factors 
which  govern  the  supply  of  and  demand  for  oxygen  in  a  polluted  stream 
of  water.  One  second  foot  of  pure  water  at  a  temperature  of  32°  F. 
is  saturated  when  it  carries  79  pounds  of  oxygen  in  solution  in  a  twenty- 
four  hour  period,  whereas  at  a  temperature  of  86°  F.,  it  is  saturated 
when  it  carries  41  pounds  of  oxygen  in  solution.  On  the  other  hand, 
the  activity  of  the  bacteria  which  destroy  the  putrescible  matter,  is  al- 
most nil  at  32  degrees  F.,  whereas  at  86  degrees  F.,  they  are  exceedingly 
active.  It  is  thus  apparent  that  in  cold  weather  there  is  a  large  oxygen 
content  in  the  water  and  a  low  rate  of  demand,  whereas  in  warm 
weather  there  is  a  low  oxygen  content  in  the  water  and  a  high  rate  of 
demand. 

R  e  aeration: 

An  additional  factor  in  the  recovery  of  a  stream  from  pollution  is 
that  of  reaeration,  which  is  more  rapid  in  warm  weather  than  in  cold, 
and  also  increases  with  the  degree  of  depletion;  i.  e.,  if  the  water  is 
saturated,  there  will  be  no  reaeration,  if  it  has  a  zero  saturation,  the 
reaeration  will  be  at  a  maximum  for  any  given  condition,  and  the  rate 
of  reaeration  will  decrease  as  the  oxygen  deficit  decreases.  Other  fac- 
tors affecting  reaeration  are  turbulence  and  depth,  the  replenishment  in- 
creasing with  the  turbulence  and  decreasing  with  the  depth. 

Example  of  Oxygen  Requirement: 

As  a  concrete  example  of  the  relation  of  the  oxygen  demand  of  a 
sewage  and  the  oxygen  supply  of  a  stream,  it  will  be  assumed  that  one 
second  foot  of  sewage  per  day,  or  a  total  of  646,000  gallons  has,  by  the 
biochemical  ox3^gen  demand  test,  been  shown  to  require  820  pounds  of 
oxygen  to  destroy  its  putrescible  matter,  and,  that  it  is  desired  to  mix 
this  second  foot  of  sewage  with  enough  second  feet  of  saturated  water 


so 


at  86  degrees  F.  to  supply  all  the  oxygen  required.  The  one  second 
foot  of  sewage  per  day  require^  820  pounds  of  oxygen  and  one  second 
foot  of  water  per  day  at  86  degrees  F.  will  supply  41  pounds  of  oxygen, 
consequently  twenty  second  feet  of  water  will  be  required,  neglecting,  of 
course,  reaeration. 

Reaeration  is  no  doubt  a  big  contributor  to  the  total  oxygen  re- 
quired to  destroy  putrescible  matter  in  a  stream,  but,  as  it  has  a  value 
which  is  a  resultant  of  depth  of  water,  turbulence,  temperature,  and 
degree  of  depletion,  it  is  difficult  to  give  it  quantitative  expression.  The 
efficacy  of  reaeration  in  preventing  complete  depletion  of  oxygen  in  a 
stream  is  probably  closely  related  to  the  excessive  demand  for  oxygen 
which  occurs  during  the  early  stages  of  the  incubation  of  the  sewage 
and  stream  water. 

The  results  of  many  studies  of  the  oxygen  demand  of  mixtures  of 
pure  water  and  sewage  when  incubated  in  closed  containers,  which  pre- 
vent reaeration,  have  indicated  that  on  the  basis  of  the  total  amount  of 
oxygen  absorbed  in  twenty  days  at  twenty  degrees  C,  twenty-one  per- 
cent will  be  required  the  first  day,  sixteen  percent  the  second  day,  thir- 
teen percent  the  third  day,  eleven  percent  the  fourt  day  and  seven  per- 
cent the  fifth  day,  making  a  total  of  sixty-eight  percent  for  the  first  five 
days.  The  second  five  days  will  require  twenty-two  percent  of  the  total 
and  the  next  ten  days,  ten  percent  of  the  total  of  which,  however,  but 
three  percent  is  required  in  the  last  five  days. 

These  rates  are  indicative  of  a  general  average  result  rather  than 
absolutely  specific,  and  are  given  to  show  the  need  for  a  good  supply  of 
oxygen  during  the  first  few  days  of  contact  between  sewage  and  stream 
water.  In  converting  a  given  oxygen  demand  value  secured  by  a  given 
period  of  incubation,  to  an  oxygen  demand  value  for  a  longer  or  shorter 
period  of  incubation,  the  above  rates  of  satisfaction  have  been  used,  as 
the  results  of  experimental  studies  in  many  places  have  shown  them  to 
be  reasonably  reliable. 

If  the  supply  of  oxygen,  which  the  diluting  water  carries  in  solu- 
tion, is  insufficient  to  meet  the  needs  of  the  wet  combustion  process 
which  takes  place  in  a  polluted  stream,  reaeration  conditions  may  be 
such  that  the  oxygen  supplied  in  that  way  will  be  used  up  as  fast  as  it 
is  absorbed  and  distributed  and  the  water  of  the  stream  will  be  left  in  a 
condition  of  zero  saturation. 

With  these  considerations  in  mind,  a  study  of  daily  oxygen  require- 
ments of  the  sewage  of  the  Sanitary  District  of  Chicago  has  been  made, 
and  the  results  of  this  study  are  herewith  presented. 


51 


Load  of  Sanitary  District: 

There  are  two  ways  of  expressing'  the  daily  oxygen  requirements, 
namely,  as  a  definite  number  of  pounds  of  oxygen  per  person  per  day, 
or,  as  a  total  number  of  pounds  of, oxygen  per  day  for  the  entire  district. 

The  determination  of  the  total  daily  oxygen  load  from  a  represen- 
tative district  divided  by  the  population  contributing  to  this  load,  will 
give  a  per  capita  daily  load  which  may  be  applied  to  the  whole  district. 
In  the  event  that  there  are  large  industrial  loads  that  have  a 
marked  effect  on  the  total  load,  such  industrial  loads  should  be  deter- 
mined separately  and  added  to  the  total  load  as  estimated  from  the  rep- 
resentative  district,  in  which  event,  the  human  population  per  capita 
load  will  be  increased,  or,  the  industrial  loads  may  be  converted  into  an 
industrial  equivalent  population  load,  in  which  case  the  human  popula- 
tion plus  the  industrial  equivalent  population  times  the  human  population 
per  capita  load  will  give  the  total  load. 

A  common  way  of  expressing  an  industrial  load  is  to  convert  it 
into  an  equivalent  human  population,  but  in  order  to  avoid  confusion, 
no  use  has  been  made  of  the  industrial  equivalent  population. 

The  sewage  of  the  entire  Sanitary  District  of  Chicago  is  discharged 
by  approximately  150  sewers,  varying  in  diameter  from  two  feet  to 
sixteen  feet,  into  the  north  and  south  branches  of  the  Chicago  River,  the 
Des  Plaines  River,  the  Calumet  River,  and  the  Drainage  Canal,  making 
it  very  difficult  to  get  an  accurate  determination  of  the  sewage  flow  of 
the  entire  district. 

Thirty-Ninth  St.  Studies  1914: 

During  the  year  1914,  hourly  samples  of  sewage  were  taken  at  the 
39th  St.  sewage  pumping  station,  and  dosed  with  nitrate  solution  of 
known  concentration,  then  allowed  to  incubate  for  ten  days.  At  the  end 
of  the  ten-day  period  of  incubation,  the  twenty-four  hourly  samples  were 
composited  without  correction  for  flow  fluctuations  and  the  residual 
nitrite  and  nitrate  determined  on  the  composite  sample.  The  oxygen 
demand  value  secured  in  this  way  was  taken  as  the  mean  value  for  the 
day.  The  incubation  was  not  carried  out  at  a  constant  temperature,  but 
at  whatever  temperature  happened  to  exist  where  the  incubating  samples 
were  stored. 

The  average  oxygen  demand  as  determined  in  this  manner  after  a 
ten-day  incubation  was  found  to  be  121  parts  per  million,  which  means 
that  121  pounds  of  oxygen  would  be  required  to  destroy  the  putrescible 
matter  in  one  million  pounds  of  sewage,  or  1008  pounds  of  oxygen 
would  be  required  for  one  million  gallons  of  sewage.  The  average  rate 
of  pumpage  was  found  to  be  71  million  gallons  per  day  (  or  *219  gals. 


*Note — Total  XDity  pumpage  year  1914,  2.54  g-als.  per  capita. 


52 


per  capita),  and  this  was  secured  by  taking  the  daily  records  of  the 
speed  of  the  pumps  and  determining  the  discharge  by  using  the  manu- 
facturer's speed,  capacity,  and  head  curves.  There  is  some  doubt  as  to 
the  accuracy  of  this  method  in  determining  the  discharge  of  the  pumps. 

The  population  of  the  district  contributing  sewage  to  this  station  was 
estimated  at  324,000.  On  the  basis  of  the  above  data  the 
daily  per  capita  oxygen  load  was  1008  pounds  times  71  M.  G., 
divided  by  v324,000  or  0.22  pounds  of  oxygen,  on  a  ten-day  oxygen  de- 
mand basis. 

Thirty-Ninth  St.  Studies,  1920: 

Between  November  8th,  1920,  and  December  11th,  1920,  a  similar 
investigation  was  made  at  the  39th  St.  sewage  pumping  station.  The 
oxygen  demand  was  determined  by  the  dilution  method  after  a  ten-day 
incubation  at  a  constant  temperature  of  twenty  degrees  centigrade. 
Samples  were  taken  hourly,  with  four  consecutive  hourly  samples  com- 
posited for  a  single  oxygen  demand  test.  Six  composited  samples  per 
day  w^ere  subjected  to  the  oxygen  demand  test,  and  the  mean  of  the  six 
values  was  taken  as  the  daily  mean  value.  No  attempt  was  made  to 
weight  samples  to  conform  with  hourly  flow  fluctuations. 

The  average  oxygen  demand  after  a  ten-day  incubation  at  20  de- 
grees C,  was  found  to  be  140  parts  per  million,  which  means  that  1166 
pounds  of  oxygen  would  be  required  to  destroy  the  putrescible  matter  in 
one  million  gallons  of  sewage.  The  average  rate  of  pumpage  was 
found  to  be  86.17  million  gallons  per  day  (  or  *207  gals,  per  capita), 
the  same  being  estimated  as  in  the  previous  test.  The  population  was 
estimated  to  be  417600  and  on  the  basis  of  the  above  data  the  daily  per 
capita  ox3^gen  load  was  1166  pounds  times  86.17  M.  G.  divided  by 
417600  or  0.24  pounds  of  oxygen  on  a  ten-day  oxygen  demand  basis. 

Des  Plaines  Studies: 

The  operating  results  for  the  Des  Plaines  treatment  works  for  the 
year  1924  show  an  average  daily  sewage  flow  of  four  million  gallons, 
an  average  ten-day  oxygen  demand  of  153  and  a  tributary  population  of 
40000  and  on  the  basis  of  the  above  data  the  daily  per  capita  oxygen 
load  was  153  pounds  times  8.33  times  4  M.  G.  divided  by  40000  or  0.127 
pounds  of  oxygen  on  a  ten  day  oxygen  demand  basis. 

Calumet  Studies:  : 

The  operating  results  for  the  Calumet  treatment  works  for  the  year 
1924,  show  an  average  daily  sewage  flow  of  thirty  million  gallons,  an 
average  ten-day  oxygen  demand  of  eighty  and  a  tributary  population 


*Note — Total  city  pumpage  year  1920,  27G  gals,  per  capita. 


53 


of  107,000,  and  on  the  basis  of  this  data,  the  daily  per  capita  oxygen  load 
was  80  pounds  times  8.33  times  30  M.  G.  divided  by  107000  or  0.187 
pounds  of  oxygen. 

Comparison  with  Other  Cities: 

In  Table  8,  a  comparison  may  be  made  between  Chicago  sewage  and 
that  of  other  American  and  English  cities.  It  is  quite  apparent  from 
the  data  contained  in  this  table  that  Chicago  sewage  is  considerably 
stronger  than  the  average  strength  of  sewages  listed  in  the  table. 

Industrial  Load: 

The  Chicago  industrial  load  is  quite  large  in  the  aggregate,  the 
principal  elements  of  which,  in  the  order  of  their  magnititde,  are  as 

TABLE  8 

TABLE  SHOWING  THE  STRENGTH  OF  MUNICIPAL  SEWAGES  ON  THE 
BASIS  OF  THE  OXYGEN  REQUIREMENT  IN  POUNDS  PER 
CAPITA  PER  DAY 

Gallons 


sewage 

5-Day 

Pounds 

per  capita 

oxygen 

oxygen 

per  day  by 

demand 

required 

contributing 

in 

per  capita 

Ref.  City 

population 

P.  P.  M. 

per  day 

  131 

92 

0.100 

Baltimore,  Md  

  106 

120 

0.106 

Canton,  Ohio  

  64 

213 

0.113 

Columbus,  Ohio  

  94 

190 

0.148 

  88 

155 

0.114 

  89 

144 

0.107 

  101 

118 

0.099 

Rochester,  N.  Y  

  137 

104 

0.119 

B     Malton,  Eng  

  40 

467 

0.155 

C    Huntingdon,  Eng  

  27 

475 

0.107 

D    Brooklyn,  N.  Y  

  102 

223 

0.189 

Min.  value 

0.099 

Max.  value 

0.189 

  35 

350 

0.102 

Strong  Eng.  Sewage  

  35 

500 

0.146 

  206 

106 

0.182 

G  Chicago   

  219 

91 

0.167 

H  Chicago  

  100 

122 

0.102 

I  Chicago   

  280 

64 

0.149 

References:     A.    U.  S.  Public  Health  Service  Bull.,  No.  132,  p.  115. 

B.  Eighth  Report  Roy.  Com.  Sew.  Disp.  Vol.  2,  Appendix,  pages  27,  68,  81.. 

C.  Eighth  Report  Roy.  Com.  Sew.  Disp.  Vol.  2,  Appendix,  page  20. 

D.  Brooklyn,  N.  Y.  Sewage  Treatment  Experiments  by  George  T.  Hammond, 

Reprinted  from  1919  Proc.  Am.  Soc.  Mun.  Improvements,  p.  20  and  22 
of  Reprint. 

E.  Eighth  Rept.  Roy.  Com.  Sew.  Disp.  Vol.  1,  page  9. 

F.    Operation  data,  39th  St.  Sew.  Pump.  Sta.  Year  1920. 

G.  Operation  data,  39th  St.  Sew.  Pump.  Sta.  Year  1914. 

H.  Operation  data  Des  Plaines  Sewage  Treatment  Works,  Year  1924. 

I.  Operation  data  Calumet  Sewage  Treatment  Works  Year  1924. 


54 


follows :  Stockyards  and  Packingtown  wastes,  corn  products  wastes, 
tannery  wastes,  wool  pulling  and  washing  wastes,  and  numerous  other 
smaller  industrial  wastes,  many  of  which  are  common  to  all  large  cities. 
The  Stockyards  and  Packingtown  wastes  and  the  corn  products  wastes 
have  been  and  are  now  being  extensively  studied  by  the  sanitary  en- 
gineering division  of  the  Sanitary  District  and  the  conclusions  which 
they  have  arrived  at  may  be  summarized  as  follows : 


The  sewage  flow  from  the  packing  industries  is  based  on  numer- 
ous sewer  gagings  and  the  oxygen  demand  is  an  average  value  of  numer- 
ous determinations  made  between  the  years  1911  and  1918,  all  of  which 
data  is  reported  in  detail  in  the  Reports  on  Industrial  Wastes  from  the 
Stockyards  and  Packingtown,  Vol.  1  having  been  issued  in  October, 
1914,  and  Vol.  2  in  January,  1921. 

The  tannery  and  other  miscellaneous  wastes  of  the  Sanitary  Dis- 
trict of  Chicago  have  been  estimated  by  officials  of  the  Sanitary  District 
to  have  a  daily  oxygen  requirement  of  40,000  pounds. 

The  total  industrial  load  of  the  district  has  been  estimated  by  offi- 
cials of  the  Sanitary  District  to  have  a  daily  oxygen  requirement  of 
367,000  pounds. 

Canal  Studies: 

An  entirely  separate  study  of  the  Chicago  load  has  been  made  by 
investigations  conducted  at  several  points  along  the  canal  between 
Brandon  Bridge  below  Joliet,  and  Summit.  In  these  studies  the  load 
was  estimated  by  determining  the  oxygen  lost  from  the  mixture  of  lake 
water  and  sewage  to  a  given  station  or  observation  point,  and  adding 
this  load  to  the  unsatisfied  demand  at  the  station.  The  sewage  flow 
was  an  assumed  value,  the  dissolved  oxygen  content  of  the  sewage  was 
assumed,  the  dissolved  oxygen  content  of  the  diluting  water  was  de- 
termined by  analysis,  the  total  flow  of  the  canal  was  taken  from  a  rating 
curve  for  a  U.  S.  G.  S.  gaging  station,  and  all  other  values  were  deter- 
mined by  analysis.  The  results  of  these  studies  as  well  as  all  other 
studies  of  the  Chicago  load,  which  have  been  investigated,  are  recorded 


Estimated  average 
daily  sewage  flow 
in  million  gallons 
for  year  1925 


Average 
10-day  oxy- 
gen demand 


value 
900 
600 


Pounds 
oxygen 
required 
per  day 
250,000 
77,000 
327,000 


Stockyards  Avastes  . . . 
Corn  Products  wastes 
Total   


33.5 
15.5 
49.0 


in  Table  10. 


55 


An  inspection  of  the  data  in  Table  10  shows  that  the  daily 
oxygen  load  as  estimated  from  the  results  of  canal  studies  varies  as 
follows : 

1.  On  basis  of    5  day  oxygen  demand—  886000  to  1195000  pounds 

2.  On  basis  of  10  day  oxygen  demand— 1117000  to  1580000  pounds 

3.  On  basis  of  20  day  oxygen  demand — 1266000  to  1760000  pounds 


TABLE  9. 

SHOWING  INDICATED  TOTAL  OXYGEN  LOAD  BASED  ON 
LOCKPORT  DATA. 


July 

August 

Febr'y 

1922 

1922 

1922 

Temp,  lake  water,  degrees  C*  (temp.)  

22.4 

23.8 

1.0 

Oxygen  in  lake  water,  P. P.M.*  (ave.)  : . . . 

8.45 

7.88 

12.37 

Oxygen  found  at  Lockport  in  P.P.M  

0.01 

0.01 

9.11 

8.44 

7.87 

3.26 

Total  flow  in  second  feet  

8696 

8360 

8330 

Assumed  sewage  flow  in  sec.  ft  

1220 

1220 

1220 

Dilution  factor  at  Lockport  

7.1 

6.85 

6.8 

B.O.D.  value  reduction  to  Lockport  (in  1220 

sec.  ft.)   

60 

54 

22 

B.O.D.  value  at  Lockport — 5  day  value  

11.20 

11.88 

23.46 

B.O.D.  value  at  Lockport,  corrected  to  1220 

sec.  ft. — 5  day  value  

80 

81 

160 

Total  B.O.D.  value  at  sewer  outlets-5  day  value 

140 

135 

182 

Total  daily  oxygen  load  in  pounds  

919,000 

886,000 

1,195,000 

*Average9  found  to  prevail  in  these  calendar  months. 


A  further  inspection  of  this  table  will  show  that  the  average  daily 
oxygen  load  of  studies  Nos.  7,  8,  9,  and  10  (warm  weather  period) 
based  on  the  20-day  demand  values,  is  1,300,000  pounds  and  that  the 
average  daily  load  of  studies  Nos.  5  and  6  (cold  weather  period)  based 
on  the  20-day  demand  values,  is  1,600,000  pounds.  In  view  of  the  fact 
that  there  was  a  marked  oxygen  depletion  at  the  points  of  observation 
during  the  warm  weather  tests,  and  probably  a  considerable  amount  of 
replenished  oxygen  used  in  satisfying  the  demand  up  to  the  observation 
station,  and  that  this  condition  did  not  obtain  to  such  a  marked  degree 
in  the  cold  weather  tests,  it  seems  probable  that  the  total  indicated  load 
of  1,600,000  pounds  of  oxygen  is  more  nearly  correct  for  the  year  1922. 
The  average  daily  oxygen  load  based  on  the  10  day  oxygen  demand 
values  and  the  cold  weather  tests  is  1,450,000  pounds  and  the  average 
daily  oxygen  load  based  on  the  5-day  oxygen  demand  values  and  the  cold 


56 


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57 


weather  tests  is  1,092,000  pounds.  Taking  human  population  for  1922 
as  3,100,000,  the  oxygen  load  per  capita  per  day  was  as  follows : 


Taking  the  human  population  for  1925  as  3,355,000,  the  total  oxy- 
gen load  per  day  for  the  year  1925,  would  be  as  follows : 

On  basis  of  20-day  demand  value ....  1,730,000  pounds 
On  basis  of  10-day  demand  value.  ...  1,570,000  pounds 
On  basis  of    5-day  demand  value.  ...  1,180,000  pounds 

Resume  of  Studies: 

In  Table  11  are  shown  comparative  data  on  the  oxygen  re- 
quirements of  the  sewage  of  the  Sanitary  District  of  Chicago,  as  deter- 
mined from  three  separate  sources. 

In  the  studies  conducted  by  the  U.  S.  PubHc  Health  Service  during 
the  year  1922,  samples  were  taken  from  the  canal  at  Lockport  between 
6  a.  m.  and  8  a.  m.,  and  the  oxygen  demand  determined  after  a  5-day 
period  of  incubation  at  a  constant  temperature  of  twenty  degrees  C. 
These  studies  were  completed  in  August,  1922,  and  some  doubt  existed 
as  to  the  single  samples  being  representative.  The  Sanitary  District  of 
Chicago  was  asked  to  make  a  study  which  would  show  whether  there 
was  a  fluctuation  in  strength  during  a  twenty-four  hour  period. 

A  study  to  determine  this  was  made  by  the  Sanitary  District  during 
September,  October,  and  November,  1922,  samples  being  taken  at  the 
same  sampling  point  at  Lockport  as  that  from  which  the  U.  S.  P.  H.  S. 
samples  were  taken,  and  at  4  a.  m.,  8  a.  m.,  noon,  4  p.  m.,  8  p.  m.,  and 
12  p.  m.  daily.  The  oxygen  demand  was  determined  on  each  sample 
by  a  5-day  incubation  at  a  constant  temperature  of  20  degrees  C 

A  curve  was  plotted  showing  the  daily  fluctuations  at  four  hour 
intervals  and  another  curve  was  plotted  to  show  the  fluctuations  of  the 
flow  during  this  period.  From  these  two  curves  a  correction  factor  of 
1.27  was  evolved  to  apply  to  the  single  daily  sample  taken  from  6  a.  m. 
to  8  a.  m.  to  make  the  oxygen  demand  representative. 

An  hourly  fluctuation  curve  for  oxygen  demand  resulting  from  the 
temperatures  obtaining  in  the  canal  water  in  September,  October,  and 
November  will  probably  be  different  from  a  similarly  plotted  curve  for 
warmer  or  colder  weather ;  consequently  it  is  believed  that  this  particu- 
lar oxygen  demand  curve  is  not  suitable  or  reliable  for  full  year  appli- 
cation. The  load  value  secured  in  this  way  is  less  convincing  than  it 
would  be  had  the  results  been  based  on  weighted  daily  composites,  and 
it  is  impossible  to  say  whether  the  indicated  load  is  too  high  or  too  low. 


On  basis  of  20-day  demand  value 
On  basis  of  10-day  demand  value 
On  basis  of    5-day  demand  value 


0.516 
0.468 
0.352 


58 


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59 


The  determination  of  the  daily  load  from  the  results  of  the  opera- 
tion of  the  Calumet  and  Des  Plaines  sewage  treatment  works  for  the 
year  1924,  would  be  open  to  criticism  because  the  use  of  a  per  capita 
value  secured  from  these  results  would  result  in  adopting  a  load  value 
from  about  three  percent  of  the  population  of  the  district  and  calling  it 
representative. 

Best  Criterion  for  Domestic  Load: 

The  determination  of  the  daily  domestic  load  from  the  results  of 
the  1920  studies  of  the  39th  Street  sewer  seems  at  this  time  to  be  the 
most  logical  course  to  pursue  for  the  following  reasons : 

1st.  The  district  contributing  to  this  sewer  is  considered  to  be 
reasonably  representative. 

2nd.  The  study  was  made  during  a  census  year  and  for  this  reason 
a  reasonably  accurate  estimate  of  the  contributing  population  could  be 
made. 

3rd.  The  analytical  data  is  complete  and  satisfactory  for  use  in 
determining  the  load. 

4th.  The  pumpage  record  is  not  thought  to  be  very  accurate  and 
the  average  daily  flow,  if  in  error,  is  believed  to  be  too  high,  and  if  this 
is  true  the  indicated  load  is  too  high  and  the  error  is  on  the  side  of 
safety. 

5th.  The  population  contributing  to  this  sewer  is  approximately 
ten  percent  of  the  total  population  of  'the  district. 

From  the  data  which  has  been  reviewed,  it  is  thought  that  the  load 
values  as  shown  in  Table  11  for  the  39th  Street  sewer  are  the  most 
dependable.  Furthermore,  it  is  thought  that  a  carefully  planned  study 
of  the  canal  at  Lockport  or  at  some  other  location  or  locations  would 
result  in  a  more  reliable  determination  of  the  daily  load,  and  these 
studies  would  also  provide  a  check  on  the  previous  studies  of  the  Stock- 
yards and  Corn  Products  wastes. 

Summarized  Conclusions  on  1925  and  Projected  Daily  Loads: 

In  estimating  the  total  daily  load  of  the  entire  Sanitary  District  for 
the  year  1925,  and  projecting  these  loads  at  five  year  intervals  to  1945, 
the  following  basic  data  have  been  accepted  and  used : 

1.  The  1920  results  at  the  39th  St.  sewer  which  show  the  daily 
domestic  load  to  be  0.24  pounds  of  oxygen  per  capita  per  day  on  a  ten- 
day  oxygen  demand  basis. 

2.  The  human  population  estimates  of  the  Sanitary  District  for 
five-year  intervals  from  1925  to  1945. 

3.  A  value  of  900  for  ten-day  oxygen  demand  for  the  packing 
and  stockyards  industrial  wastes,  and  the  assumption  that  the  strength 


60 


of  this  waste  will  not  change  materially  during  the  period  of  time 
involved. 

4.  The  estimate  of  the  Sanitary  District  relative  to  the  present 
daily  volume  of  the  Packingtown  and  Stockyards  wastes  for  the  years 
1925  and  1945,  which  volumes  are  respectively  thirty-three  and  one-half 
and  40  million  gallons  per  day. 

5.  A  value  of  600  for  the  ten-day  oxygen  demand  for  the  corn 
products  wastes  and  the  assumption  that  the  strength  of  this  waste  will 
not  change  materially  during  the  period  of  time  involved. 

6.  The  estimate  of  the  Sanitary  District  relative  to  the  present 
daily  volume  of  the  corn  products  wastes  for  the  years  1925  and  1945 
which  volumes  are  respectively  15  and  19  milHon  gallons  per  day. 

The  oxygen  demand  values  for  the  Packingtown  and  corn  products 
wastes  are  accepted  after  a  study  of  the  many  analyses,  which  have  been 
made  over  a  period  of  years.    The  actually  determined  value  for  the 


Dav5  of  Incubation  at2o°c. 


*  G.  L.  Fugate,  Eng.  News-Record  94,  No.  11. 
t  Data  by  Sanitary  District  of  Chicago. 

Figure  16— Biochemical  oxygen  demand  based  on  various  periods 

of  incubation. 


61 


packing  wastes  is  900  parts  per  million  for  ten-days  at  20  degrees  C 
The  value  of  680  for  the  five-day  demand  at  20  degrees  C;  is  a  calcula- 
ted value  which  was  furnished  from  the  laboratory  of  the  Sanitary 
District.  The  twenty-day  value  was  secured  by  dividing  the  ten-day 
value  by  0.90. 

The  basis  for  determining  the  load  from  the  corn  products  plant 
was  a  determined  five-day  oxygen  demand  value  of  450  and  a  calculated 
ten-day  value  of  600,  both  values  being  furnished  from  the  laboratory 
of  the  Sanitary  District.  The  twenty-day  value  was  secured  by  divid- 
ing the  ten-day  value  by  0.90. 

The  basis  for  determining  the  domestic  load  was  the  determined 
ten-day  oxygen  demand  value  of  140  for  the  39th  St.  sewer  in  1920. 
The  five  day  and  twenty-day  values  were  calculated  by  using  a  rate  of 
satisfaction  as  follows: 

5-day  value  68%  of  20-day  value 
10-day  value  90%  of  20-day  value 
20-day  value  100%  of  20-day  value 

A  curve  of  oxygen  demand  for  packing  wastes  of  Chicago  and 
Houston,  Texas,  corn  products  wastes  of  Chicago,  and  39th  St.  sewage 
of  Chicago  accompanies  this  report. 

Table  12  contains  a  summary  of  the  estimated  daily  oxygen  loads 
of  the  domestic  sewage,  stockyards  waste,  and  corn  products  waste,  the 
sum  of  which  is  taken  as  the  total  daily  load  of  the  entire  district. 

It  will  be  noted  in  this  table  that  the  total  daily  load  is  shown  on 
the  basis  of  5,  10,  and  20  day  demand  values,  the  20-day  value  indicating 
what  might  be  termed  a  substantially  complete  oxygen  requirement, 
although  it  is  not  strictly  an  absolute  value. 

Although  the  total  load  as  indicated  by  the  20-day  value  must  be 
disposed  of  finally,  it  is  not  required  that  this  amount  of  oxygen  must  be 
supplied  as  an  initial  content  in  lake  water,  as  reaeration  may  be  ex- 
pected to  contribute  a  substantial  portion  of  the  total  oxygen  required. 

The  rate  of  oxygen  satisfaction  occurring  from  the  beginning  to 
the  completion  of  a  20-day  period  of  incubation  in  closed  containers, 
which  has  been  referred  to  previously  in  this  discussion,  has  been  found 
by  a  number  of  investigators  to  be  reasonably  reliable  on  a  general 
average  basis.  These  rates  of  oxygen  satisfaction  grouped  for  five-day 
intervals  indicate  the  following  period  rates : 

1st.  5  days — 68%  of  20-day  requirement 

2nd.  5  days — 22%  of  20-day  requirement 

3rd.  5  days —  7%  of  20-day  requirement 

4th.  5  days —  3%  of  20-day  requirement 


62 


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63 


The  above  rates  indicate  that  the  demand  for  oxygen  during  the 
first  quarter  of  the  20-day  period  is  quite  high  and  a  substantial  per- 
centage of  the  total  required  for  a  reasonably  complete  destruction  of 
the  polluting  material. 

The  first  5-day  period  is  also  one  in  which  poor  reaeration  condi- 
tions would  be  most  apt  to  cause  serious  conditions  in  a  stream  through 
oxygen  depletion  resulting  from  a  rapid  rate  of  demand  and  a  slow 
rate  of  replenishment. 

A  study  of  the  daily  rates  within  the  first  5  days  shows  that  approx- 
imately fifty-five  per  cent  of  the  total  5-day  requirement  must  be  met 
during  the  first  two  days. 

Quite  a  number  of  laboratory  studies  of  mixtures  of  sewage  and 
clean  water  incubated  in  open  containers  have  shown  invariably  that 
where  a  proper  dilution  was  used  and  in  which  enough  initial  oxygen 
was  present  to  supply  the  needs  for  the  first  two  days,  an  increase  in 
dissolved  oxygen  content  began  after  the  first  two  days  of  incubation. 

Criterion  for  Load: 

In  view  of  such  evidence  as  has  been  available  and  on  the  basis  of 
the  observed  behavior  of  mixtures  of  sewage  and  clean  water  which 
have  been  shown  to  have  reasonably  definite  general  average  rates  of 
demand  for  oxygen,  it  is  considered  that  a  supply  of  dilution  water 
having  an  initial  oxygen  content  equal  to  the  total  5-day  oxygen  demand 
load  of  the  Sanitary  District  will  be  sufficient  and  satisfactory. 

For  the  above  reasons,  and  for  the  reasons  more  fully  stated  in 
Part  V  and  Part  VI,  we  conclude  that  the  5-day  biochemical  oxygen 
demand  of  the  sewage,  and  purification  plant  effluents,  will  furnish  the 
most  useful  criterion  of  organic  load. 


64 


PART  V. 

STANDARD  OF  MAXIMUM  POLLUTION 

It  is  desirable  that  a  standard  should  be  fixed  to  measure  the  eflPec- 
tiveness  of  means  to  be  taken  to  prevent  excessive  pollution  of  the 
rivers  below  Joliet.  This  standard  should  be  applicable  whether  the 
protective  measures  consist  of  dilution  from  Lake  Michigan,  sewage 
treatment  works,  or  both.  It  will  be  most  desirably  and  conveniently 
applied  at  the  foot  of  the  Drainage  Canal.  A  test  must  cover  a  period 
sufficiently  long  to  represent  conditions  which  might  create  a  nuisance, 
to  eliminate  unavoidable  errors  in  sampling,  and  to  average  up  ordinary 
variations  that  might  be  caused  by  excessive  discharge  frorri  the  storm 
sewers. 

It  is  regarded  as  essential  that  the  standard  should  exclude  settle- 
able  suspended  matters  of  an  organic  character ;  otherwise  deposits  in 
the  stream  below  Lockport,  in  the  colder  weather,  will  tend  to  rob  the 
stream  of  oxygen  in  summer,  thus  producing  undesirable  conditions,  the 
magnitude  of  which  is  not  subject  to  prediction. 

Subject  to  the  above  requirement,  it  is  believed  to  be  practicable  to 
prescribe  an  oxygen  content  and  an  organic  load,  which,  aided  by  re- 
aeration  and  added  dilution  from  streams  below  Lockport,  will  permit  of 
satisfactory  stream  conditions  at  all  places  on  the  Illinois  and  Des 
Plaines  Rivers,  including  freedom  from  nuisance,  conditions  tolerable 
for  fishes  in  the  Des  Plaines  and  Upper  Illinois,  and  such  as  to  permit 
a  thriving  fish  fife  in  the  lower  Illinois. 

Limitations  of  Standard: 

In  fixing  a  standard  to  be  used  as  a  governing  basis  for  the  pollu- 
tion of  the  Illinois  River,  both  now  and  hereafter,  there  are  two  con- 
siderations that  should  be  set  forth  clearly  in  the  beginning : 

1st.  It  is  economically  impractical  to  expect  that  the  IlHnois  River 
should  be  returned  to  a  condition  such  as  exists  in  streams  which  receive 
no  pollution  at  all ;  i.  e.,  to  a  condition  of  pristine  purity. 

2nd.  The  existence  of  any  appreciable  amount  of  settleable  pu- 
trescible  material  in  the  drainage  course  is  apt  to  upset  all  eflforts  which 
are  aimed  at  the  maintenance  of  proper  stream  conditions  through 
sewage  treatment  and  regulated  diversion. 


65 


During  the  year  1922,  the  U.  S.  Public  Health  Service  made  a  care- 
ful and  systematic  study  of  the  condition  of  the  waters  of  the  Illinois 
River  and  its  tributaries. 

Condition  of  Illinois  River: 

The  condition  of  the  Illinois  River  was  studied  by  taking  daily 
samples  of  the  water  at  a  number  of  stations  between  Lockport  and 
Kampsville  and  determining  the  dissolved  oxygen  and  the  five-day  oxy- 
gen demand  at  twenty  degrees  C,  in  addition  to  other  determinations 
the  results  of  which  will  not  be  considered  in  this  connection.  The  av- 
erage monthly  oxygen  values  for  each  sampling  station  are  plotted  on 
Figures  5,  6,  7  and  8  to  show  winter,  spring,  summer  and  fall 
conditions  in  the  Illinois  River. 

An  inspection  of  Figure  7  shows  that  during  the  winter  months 
of  the  year  1922,  there  was  a  marked  preponderance  of  oxygen  demand 
over  the  dissolved  oxygen  supply  at  Lockport,  and  that  a  balance  of 
oxygen  supply  and  demand  was  not  reached  for  a  distance  of  approxi- 
mately 50  miles  below  Lockport.  The  dissolved  oxygen  content  of  the 
water  was,  however,  at  no  time  or  place  below  7  parts  per  million,  indi- 
cating that  a  low  rate  of  oxygen  depletion  was  taking  place  and  that 
an  absence  of  a  smell  nuisance  existed. 

An  inspection  of  Figure  8  will  show  that  during  the  spring- 
months  of  the  year,  the  same  disparity  between  oxygen  demand  and 
supply  existed  at  Lockport,  and  that  the  balance  was  reached  in  April 
29  miles  below,  in  May  100  miles  below,  and  in  June  120  miles  below 
Lockport.  The  dissolved  oxygen  in  April  was  not  below  three  and 
three-fourths  parts  per  million,  in  May  it  reached  a  low  value  of  one- 
half  of  a  part,  and  in  June  it  was  zero  at  Lockport. 

Figure  5  shows  the  summer  conditions  in  the  river  and  the 
oxygen  values  indicate  that  the  Illinois  River  was  practically  dead  for 
a  distance  of  113  miles  below  Lockport,  from  which  point  its  condition 
began  to  improve  until  an  oxygen  balance  existed  at  a  distance  of  125 
miles  below  Lockport. 

An  inspection  of  Figure  6  shows  conditions  quite  similar  to 
those  which  existed  during  the  spring  months  with  a  progressive  im- 
provement from  September  to  November.  The  oxygen  balance  was 
established  within  the  following  distances  below  Lockport ;  in  Septem- 
ber, 122  miles ;  in  October,  92  miles,  and  in  November,  52  miles,  the 
improvement  in  the  last  month  resulting  both  from  an  increase  in  dilu- 
tion and  a  reduction  in  temperature. 


66 


Condition  of  Tributaries  to  Illinois  River: 

The  condition  of  the  waters  of  the  tributaries  of  the  IlHnois  is  re- 
flected by  their  dissolved  oxygen  content  and  the  demand  for  oxygen 
when  incubated  in  closed  containers  for  5  days  at  20  degrees  C,  and 
these  values  are  recorded  in  Table  13. 

The  values  recorded  in  Table  13  are  the  mean  values  for  the 
months  indicated,  and  are  based  on  from  ten  to  fifteen  samples  per 
month  for  each  stream  so  that  the  information  thus  secured  gives  a 
very  satisfactory  index  of  the  sanitary  quality  of  the  water. 

It  will  be  noted  from  these  monthly  averages  that  in  only  three 
instances  did  the  5-day  oxygen  demand  exceed  the  dissolved  oxygen 
content,  and  the  average  relation  for  all  the  streams  was:  dissolved 
oxygen,  2.9,  oxygen  demand  1.0,  indicating  a  very  safe  relation 
between  the  oxygen  supply  and  demand. 

The  best  condition  found  among  the  several  tributaries  of  the 
Illinois  was  the  average  result  for  the  Kankakee  River,  where  the  rela- 
tion was  4.7  dissolved  oxygen  to  1.0  of  oxygen  demand. 

A  relationship  for  the  Illinois  River  such  as  the  average  relation- 
ship for  its  tributaries,  we  consider  to  be  too  severe  and  one  which  it 
would  be  impractical  to  impose  because  the  cost  involved  would  prob- 
ably be  out  of  proportion  to  the  advantages  which  would  accrue  there- 
from. 

Seasonable  Dilutions: 

It  is  a  well  known  fact  that  a  given  dilution  will  be  more  potent 
in  preventing  a  nuisance  in  a  polluted  stream  in  cold  weather  than  the 
same  dilution  will  be  in  warm  weather,  and  this  is  due  to  the  inhibiting 
effect  of  low  temperatures  on  bacterial  activity,  and  this  in  turn  reduces 
quite  materially  the  rate  at  which  oxygen  must  be  supplied. 

The  danger  of  oxygen  depletion  in  a  polluted  stream  where  a  given 
dilution  prevails,  is  very  materially  reduced  with  the  coming  of  freezing 
temperatures,  consequently  quite  a  material  reduction  in  diversion  water 
can  be  made  during  periods  of  low  temperatures.  Sufficiently  reliable 
information  is  not  available  at  this  time  upon  which  to  base  a  schedule 
of  diversions  which  might  be  applied  to  take  advantage  of  the  changing 
rates  of  oxygen  satisfaction  which  accompany  marked  changes  in 
temperature. 

An  indication  of  the  effect  of  temperature  on  the  rate  of  oxygen 
depletion  is  shown  by  the  results  of  some  laboratory  studies  conducted 
at  the  sewage  treatment  works  of  Columbus,  Ohio,  some  years  ago,  in 
which  mixtures  of  sewage  and  clean  water  were  incubated  in  closed 
containers  for  a  period  of  twenty-four  hours  at  various  temperatures. 


67 


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68 

The  results  of  these  studies  showed  the  following  rates  of  depletion, 
takino-  tlie  rate  at  the  hii^hcst  temi)erature  used  (90  degrees  F.)  as  100 
percent ;  90  degrees  F.  100  percent ;  80  degrees  F.  76  percent ;  70  de- 
grees F.  55  percent ;  60  degrees  F.  38  percent ;  50  degrees  F.  22  percent ; 
and  40  degrees  F.,  9  percent. 

If  the  above  rates  of  oxygen  depletion  are  typical  of  what  occurs 
in  the  drainage  course,  it  is  evident  that  a  very  marked  reduction  in  di- 
version water  could  be  made  during  freezing  weather ;  also  a  schedule 
of  seasonal  diversions  might  be  worked  out  which  would  materially  re- 
duce the  total  annual  diversion  required  to  meet  the  necessary  sanitary 
considerations. 

Oxygen  in  Lake  Walter: 

In  connection  with  the  possibilities  of  regulated  diversion  to  con- 
form to  temperature  conditions  and  also  to  take  advantage  of  the  greater 
amounts  of  dissolved  oxygen  which  are  present  in  cold  water,  the  fol- 
lowing table  of  typical  average  monthly  temperatures  and  dissolved 
oxygen  content  of  lake  water  is  of  interest.  The  values  given  are  mean 
monthly  averages  based  on  daily  analyses  of  lake  water  at  the  39th  St. 
Pumping  Station  from  September,  1921,  through  August,  1923. 


Temp.  Dissolved  Oxygen  Content 

Month  Degs.  C.  Parts  per  Million 


January    2.5  13.48 

February    2.5  13.17 

March    3.7  12.98 

April    8.6  11.72 

May    12.4  10.59 

June    17.4  9.28 

July    20.2  8.10 

August    21.5  7.80 

September    19.2  9.08 

October    14.2  9.55 

November    8.6  10.97 

December    4.3  12.31 


Annual  Mean    11.3  10.75 


Stability  Studies: 

The  results  of  many  years  of  river  inspection  studies  at  Columbus, 
Ohio,  have  shown  certain  relationships  which  exist  between  oxygen 
demand,  dissolved  oxygen,  and  stability  as  determined  by  the  methylene 
blue  test.    Some  of  these  relations  are  indicated  in  the  following  data: 


69 


Range  in  oxy- 
gen demand 
values,  37  deg. 

P     94.  hrc 

Ave.  Oxy.  de- 
mand value 
within  the 

Average  dis- 
solved oxy- 
gen in  water 

in  ciifn 

Per  cent  dis- 
solved oxy- 
gen is  of  oxy- 
gen demand 

Stability 
value  of 
water  as 
taken  in  situ 

25-30   

27.5 

0.00 

0.00 

3 

20-25   

22.0 

0.00 

0.00 

3 

15-20   

17.0 

0.34 

2.00 

5 

10-15   

12.1 

2.16 

18.00 

36 

7-9   

8.0 

2.07 

26.00 

62 

Below  7   

4.4 

3.92 

89.00 

84 

A  study  of  individual  samples  having  oxygen  demand  values  be- 
tween 6  and  12  and  showing  complete  stability  by  the  methylene  blue 
test,  has  indicated  that  the  dissolved  oxygen  does  not  have  to  equal  the 
oxygen  demand  value  to  insure  complete  stability,  and  a  few  instances 
have  been  noted  where  the  dissolved  oxygen  in  the  river  water  was  only 
forty  percent  of  the  oxygen  demand  yet  the  samples  showed  complete 
stability,  indicating  that  some  other  source  of  oxygen  was  available, 
probably  in  the  form  of  nitrites  or  nitrates. 

Five-Day  Value: 

As  the  relationship  between  the  rapidity  of  oxidation  in  sewage  at 
constant  temperature  is  subject  to  prediction,  approximately  from  day 
to  day,  it  would  be  possible  to  use  any  reasonable  period  of  incubation 
as  a  test  citerion.  The  period  of  five  days  has  been  frequently  used  in 
determining  the  quality  of  sewage  and  sewage  polluted  waters.  It  has 
the  advantage  over  other  periods  of  incubation  in  that  if  a  mixture  of 
sewage  and  water  contains  sufficient  oxygen  to  meet  the  five  day  oxygen 
demand  of  the  organic  matter  content,  then  the  liquid  under  ordinary 
conditions  in  streams  will  not  become  entirely  devoid  of  oxygen,  and 
thus  no  nuisance  will  be  created.  If  a  shorter  period  of  incubation 
should  be  used  as  a  criterion,  the  oxygen  content  for  equal  freedom 
from  nuisance  would  necessarily  exceed  the  biochemical  oxygen  de- 
mand. If  a  period  of  incubation  longer  than  five  days  should  be  taken, 
an  oxyben  content  less  than  the  biochemical  oxygen  demand  would  be 
justified.  Therefore,  the  use  of  the  period  five  days  as  an  index  is  a  con- 
venient period  for  use.  It  has  been  used  by  the  U.  S.  Public  Health 
Service  in  its  stream  studies  in  the  United  States,  and  it  was 
adopted  by  the  Royal  Commission  on  Sewage  Disposal  in  its  very  com- 
prehensive report  upon  "The  Sewage  Pollution  of  Streams"  in  England. 

Laboratory  Experiments : 

Certain  laboratory  experiments  at  Columbus,  Ohio,  in  connection 
with  the  sewage  disposal  problem,  bear  upon  this  point.  Table  14 
shows  certain  data  regarding  the  rapidity  of  oxygen  depletion  and  the 
recovery  thereof  with  sewage  in  open  containers. 


70 


In  the  first  two  columns  of  this  table  it  is  apparent  that  all  of  the 
oxygen  absorbed  from  the  air  was  used  up  at  once  and  this  continued 
for  six  days  in  both  the  first  and  second  tests.  In  the  third  test  it  was 
five  days  before  the  original  content  of  oxygen  was  restored,  and  in  the 
fourth  test  it  was  four  days  before  this  condition  obtained.  The  last 
three  tests  were  made  on  diluted  samples,  and  the  results  indicate  that 
the  maximum  depletion  occurred  during  the  first  two  days,  and  that 
thereafter  reaeration  and  demand  were  balanced.  The  last  three  tests 
also  show  that  the  dissolved  oxygen  is  drawn  upon  rather  heavily  before 
reaeration  becomes  a  marked  factor,  indicating  that  if  a  marked  deple- 
tion of  dissolved  oxygen  is  to  be  prevented  the  initial  oxygen  must  be 
considerably  in  excess  of  the  two-day  demand. 

Reference  in  again  made  to  the  rates  of  satisfaction  (page  50  of 
this  report)  which  is  as  follows : 

In  1  day — 21%  of  total  20-day  requirement 
In  2  days — 37%  of  total  20-day  requirement 
In  3  days — 50%  of  total  20-day  requirement 
In  4  days — 61%  of  total  20-day  requirement 
In  5  days — 68%  of  total  20-day  requirement 
TABLE  14. 

RESULTS    OF   OPEN    INCUBATION    TESTS    OF    RAW    SEWAGE  AND 
TANK   EFFLUENTS  AT  THE   SEWAGE  TREATMENT  WORKS 
AT  COLUMBUS,  OHIO. 

Dissolved  Oxygen  Content  in  Parts  per  Million  of  10  Gallon  Mixtures  After 
Incubation  in  Open  Containers  at  Room  Temperature. 


At  Start  . . 
After  1  day 


After  2  days.  . . 
After  3  days. . . 
After  4  days.  . . 
After  5  days . . . 
After  6  days . . . 
After  7  days . . . 
After  8  days.  . . 
After  9  days . . . 
After  10  days . . 


1.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.4 


0.0 
0.0 
0.0 
0.0 
0.0 
0.0 
0.4 
0.9 
1.0 
1.2 
1.4 


1.2 
0.6 
0.3 
0.4 
0.7 
1.5 
2.6 


1.2 
0.6 
0.7 
1.0 
1.6 
2.8 
3.0 
3.5 
3.8 
4.0 
4.0 


(1) 
5.3 
0.8 
0.7 
1.1 
0.8 
1.0 
1.0 


(2) 
6.8 
2.4 
3.2 
3.6 
4.0 
4.0 
3.9 


(3) 
6.9 
3.2 
3.2 
4.0 
4.0 
4.3 
4.0 


1.  Raw  sewage  one  volume,  clean  water    3  volumes. 

2.  Raw  sewage  one  volume,  clean  water    7  volumes. 

3.  Raw  sewage  one  volume,  clean  water  11  volumes. 


71 


If  the  5-day  demand  is  taken  as  the  total  oxygen  which  must  be 
supplied  by  the  dilution  water,  the  relation  is  as  follows : 


Per  cent  of  Per  cent  of 

20  day  demand  5  day  demand 


One  day    21  30.9 

Two  days    37  54.4 

Three  days    50  73.5 

Four  days   61  89.7 

Five  days    68  ♦  100.0 


Reaeration  Absent: 

The  standard  hereinafter  proposed  in  this  report  is  that  the  resi- 
dual dissolved  oxygen  and  5-day  demand  must  be  equivalent  at  Lock- 
port,  and  the  worst  condition  that  might  result  is  shown  in  the  follow- 
ing table,  and  is  based  on  the  entire  absence  of  reaeration : 


Dissolved  Oxygen  in  P.P.IVI. 

Initial       Consumed  Residual 


Start    8.0 

After  1  day   2.47  5.53 

After  2  days   4.35  3.65 

After  3  days.   5.88  2.12 

After  4  days   6.18  1.82 

After  5  days   8.00  0.00 


In  the  above  table  it  is  assumed  that  the  dissolved  oxygen  content 
of  the  water  is  8.0  parts  per  million,  and  complying  with  the  standard 
proposed  in  this  report,  the  5-day  demand  would  be  8.0  parts  per  million. 

Reaeration: 

It  is  our  belief  that  there  will  be  enough  reaeration  to  prevent  a 
serious  depletion  of  oxygen  in  the  Drainage  Canal  if  the  recommended 
standard  of  pollution  is  adhered  to. 

When  the  mixed  lake  water  and  sewage  reaches  Lockport,  in  sum- 
mer, the  purifying  action  of  the  lake  water  is  finished.  The  oxygen  con- 
tent of  the  liquid  is  practically  zero.  Nevertheless  in  its  further  flow  to 
Chillicothe,  the  total  organic  units,  passing  that  point  in  a  given  time,  are 
greatly  reduced  through  agencies  other  than  Lake  Michigan  water. 
This,  notwithstanding  the  fact  that  the  normal  load  in  the  summer 
season  is  greatly  augmented  by  river  bottom  deposits  which  have  re- 
mained in  refrigeration  during  the  colder  months. 


72 


An  analysis  of  the  studies  of  the  U.  S.  P.  H.  Service  for  the 
month  of  August,  1922,  indicate  that  the  purifying  agencies  acting  be- 
low Lockport  and  above  Chillicothe,  from  sources  other  than  Lake 
Michigan,  are  more  potent  in  total  than  the  total  diluting  water  from 
Lake  Michigan.  These  purifying  agencies  may  include  sedimentation, 
putrefaction,  and  oxidation.  In  our  opinion  oxidation  is  the  chief  fac- 
tor. This  opinion  is  reinforced  by  the  fact  that  between  Chillicothe  and 
Peoria  (in  Peoria  Lake)  a  distance  of  sixteen  miles,  the  recovery  of 
oxygen  units  in  the  water  is  nearly  as  great  as  was  obtained  in  total 
diversion  from  Lake  Michigan. 

In  addition  to  the  natural  agencies'  there  are  artificial  agencies  that 
may  be  called  into  action  if  needed  to  increase  reaeration ;  namely,  the 
fall  at  Lockport,  and  the  available  fall  at  the  several  state  dams  when 
the  Illinois  waterway  is  built.  Several  studies  of  the  river  indicate  a 
marked  recovery  in  oxygen  at  the  Marseilles  dam  where  much  of  the 
water  is  wasted  over  the  dam.  At  Lockport  it  nearly  all  passes  through 
the  water  wheels  of  the  Sanitary  District,  with  practically  no  oxygen 
gain  at  present. 

Thus  in  our  opinion  reaeration  even  of  still  water  is  a  most  impor- 
tant agency  of  purification. 

Dilution  in  Other  Cities: 

Attention  is  further  invited  to  Table  15  which  shows  the  dilu- 
tion water  available  for  several  American  cities  which  discharge  un- 
treated sewage  into  the  streams  along  which  they  are  located.  The 
data  contained  in  this  table  simply  shows  what  has  been  allowed  to  exist 
as  a  permissible  pollution  and  probably  the  conditions  created  therefrom 
in  the  several  streams  have  varied  from  satisfactory  to  doubtful. 

The  recommended  standard  contained  in  this  report  (eliminating 
for  the  moment  the  matter  of  settleable  solids)  is  that  5.9  cubic  feet  per 
second  per  1000  human  population  will  be  required  to  properly  dispose 
of  the  entire  untreated  sewage  of  the  Sanitary  District  of  Chicago  dur- 
ing the  warm  weather  season  of  the  year. 

Dilution  After  Purification: 

We  show  in  Table  16  a  Hst  of  cities  in  which  more  or  less  complete 
purification  has  been  adopted,  together  with  the  amount  of  diluting 
water  that  is  available  in  dry  weather  to  mix  with  the  purified  effluent  in 
the  stream  below  the  purification  works.  The  dilution  is  expressed  in 
cubic  feet  per  second  per  thousand  of  population  based  on  the  1920 
census. 

It  will  be  observed  that  in  several  instances  the  stream  goes  dry. 


73 


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74 


The  numerical  average  dilution  is  .58  second  feet  per  thousand 
people.  The  weighted  average  is  .42  second  feet  per  thousand  people. 
Attention  is  called  to  the  fact  that  as  these  cities  grow  the  dilution  ratio 
must  become  less,  for  in  all  cases,  so  far  as  known,  there  is  no  practicable 
means  by  which  the  dry  weather  flow  of  the  stream  will  be  increased. 

As  compared  to  the  above  figures  the  standard  recommended  in 
this  report  and  the  recommended  purification  works  contemplate  dilu- 
tions as  follows :  These  dilutions  are  expressed  in  second  feet  of  dilut- 
ing water  per  thousand  people  as  of  the  year  1935,  when  recommended 
sewage  works  have  been  completed,  and  ten  years  thereafter. 


With  total  diversion  including                    In  Year  In  Year 

dilution  water  and  sewage  of                        1935  1945 

4,167  second  feet  65  .5 

6,000  second  feet  1.1  .9 

7,500  second  feet.  1.5  1.2 

8,500  second  feet  1.7  1.4 

10,000  second  feet  2.1  1.7 


These  figures  when  compared  with  the  data  shown  in  Table  16  tend 
to  indicate  that  a  liberal  amount  of  dilution  is  provided  by  the  recom- 
mended standard  for  pollution  and  the  recommended  works  for  purifi- 
cation. It  would  appear  that  if  this  dilution  is  not  sufficient,  then  the 
satisfactory  disposal  of  sewage  in  many  of  our  inland  cities  is  impos- 
sible. 

Pollution  and  Fishes: 

It  is  evidently  desirable  that  our  streams  insofar  as  possible  should 
be  sufficiently  pure  to  permit  the  continuance  of  the  natural  water  life 
thereof,  including  the  fishes.  This  matter  is  particularly  important  in 
Illinois  River  which  has  been  the  best  fish  stream,  in  the  Middle  West. 
For  many  years  it  has  supported  a  commercial  fishery  with  a  catch 
ranging  from  ten  million  to  twenty-three  million  pounds  per  year. 
About  seventy-five  percent  "of  the  catch  has  been  the  so-called  coarser 
fishes  such  as  Carp  and  Buffalo.  The  so-called  game  fishes  have  been 
present  in  large  numbers,  and  the  Illinois  River  has  been  the  playground 
of  the  game  fisherman,  and  is  so  at  present  in  its  lower  reaches.  Of 
recent  years  the  commercial  catch  has  materially  declined  due  in  part 
to  causes  other  than  sewage  pollution. 

Inorganic  Wastes: 

^  In  certain  parts  of  the  country  inorganic  wastes  are  produced  by  in- 
dustries that  have  poisoned  the  fishes  and  entirely  destroyed  them 
throughout  long  stretches  of  streams.  Numerous  industrial  wastes  are 
poisonous  to  fishes  when  present  in  certain  amounts. 


75 


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76 


Upon  the  Illinois  River,  so  far  as  we  know,  the  inorganic  pollution 
has  not  reached  amounts  to  be  seriously  detrimental  to  fishes. 

Organic  Pollution: 

Certain  of  the  coarser  fishes  may  live  and  possibly  thrive  in  waters 
more  or  less  heavily  sewage  polluted.  There  is,  however,  a  limit  to  the 
suspended  organic  matters  present  in  waters  in  which  fishes  may  main- 
tain healthy  conditions.  All  the  fishes  and  the  attendant  train  of  water 
life  necessary  for  their  existence  are  killed,  if  the  air  supply  in  the  water 
is  reduced  to  zero  for  a  sufficient  period.  This  exhaustion  of  air  may  ^ 
result  from,  the  decomposition  of  organic  matters. 

With  a  reduction  in  the  dissolved  oxygen  carried  by  a  stream,  the 
more  sensitive  fishes,  and  ultimately  all  the  fishes  endeavor  to  get  away. 
If  escape  is  impossible  they  die.  Some  of  the  so-called  coarser  fishes 
may  tolerate  for  a  time,  conditions  in  which  oxygen  is  practically  ex- 
hausted from  the  water,  due  to  their  power  to  take,  store,  and  use  a  cer- 
tain amount  of  atmospheric  oxygen.  Other  fishes  do  not  have  this 
ability. 

During  the  winter  of  1924-5,  ice  conditions  on  the  Illinois  River  re- 
duced the  dissolved  oxygen  to  figures  as  low  as  from  .4  to  1.8  parts  per 
million.  Under  conditions  such  as  this  all  kinds  of  fish  taken  from  nets 
under  the  ice  were  found  to  be  dead.  At  another  place  where  the  water 
contained  2.5  parts  per  million  of  dissolved  oxygen,  only  Carp,  Buffalo, 
and  Gars  were  taken  alive,  all  in  a  stupid  condition.  In  another  part  of 
the  stream  where  the  oxygen  content  was  5.4  to  5.8,  all  fish  were  found 
in  good  condition  under  the  ice. 

It  is  believed  that  the  above  figures  typify  minimum  conditions  un- 
der which  the  fishes  may  survive.  They  probably  require  more  favor- 
able conditions  than  this  throughout  most  of  the  year,  in  order  to  pro- 
pagate and  thrive. 

A  study  of  the  graphs  and  tables  of  pollution  on  the  Des  Plaines 
and  IlHnois  Rivers  herein-elsewhere  shown,  coupled  with  a  knowledge 
of  the  places  where  fishes  may  now  be  found,  throw  some  light  upon 
limits  of  pollution. 

Fishing  conditions  below  Peoria  in  general  are  good.  Above 
Peoria  fishes  are  practically  extinct  except  as  follows :  In  seasons  of 
low  flow  from  the  tributary  streams,  the  dead  line  has  moved  down- 
stream to  Peoria  and  unfavorable  conditions  have  been  noted  as  far 
south  as  Havana.  In  seasons  of  maximum  flow  from  the  tributaries, 
the  dead  line  moved  upstream.  It  is  understood  that  the  1925  season 
finds  fishes  in  Peoria  Lake,  from  which  they  have  been  largely  or  en- 


77 


tirely  absent  for  several  years.  This  is  probably  due  to  the  heavy  sum- 
mer flows  in  1924. 

The  study  of  the  river  seems  to  indicate  that  where  the  dissolved 
oxygen  exceeds  the  five-day  demand  of  the  organic  matter  in  summer, 
and  considerably  exceeds  it  throughout  the  remainder  of  the  year  that 
fish  may  thrive  providing  that  the  minimum  dissolved  oxygen  at  any 
time  is  three  parts  per  million  or  more. 

In  the  works  which  we  have  suggested  for  sewage  treatment  at 
Chicago  under  various  rates  of  dilution,  and  the  standard  herein-else- 
where  set  down  for  the  liquid  discharged  by  the  Drainage  Canal  at 
Lockport,  we  believe  that  satisfactory  fish  conditions  will  be  maintained 
throughout  the  greater  part  of  the  Illinois  River.  We  believe  that  con- 
ditions will  permit  the  coarser  fishes  to  live  at  all  places  from  Joliet  to 
the  Mississippi. 

Recommended  Standard: 

After  reviewing  all  the  data  which  has  been  available  relative  to 
the  past  conditions  which  have  prevailed  in  the  Illinois  River  below 
Lockport,  in  addition  to  the  studies  which  have  been  made  and  which 
indicate  the  sanitary  quality  of  the  waters  of  the  streams  which  are  trib- 
utary to  the  Illinois ;  and,  with  the  purpose  in  view  of  seeking  a  reason- 
able degree  of  cleanness  in  the  Illinois  River  below  the  terminus  of  the 
drainage  canal ;  and,  in  the  belief  that  the  maintenance  of  such  condition 
is  not  prohibitive  in  cost  or  unduly  difficult  of  attainment ;  the  following 
standards  of  maximum  pollution  are  proposed : 

The  liquid  discharged  by  the  Drainage  Canal,  as  evidenced  by  the 
average  of  representative  samples  taken  for  any  thirty  consecutive  days 
shall: 

(a)  Be  practically  free  from  settleable  solids  deposited  in  two 
hours  and 

(b)  Shall  contain  dissolved  oxygen  equal  to,  or  exceeding,  the  bio- 
chemical oxygen  demand  of  said  Hquid  for  five  days  when  incubated  at 
twenty  degrees  Centigrade. 

(c)  Shall  contain  not  less  than  three  parts  per  million  of  dissolved 
oxygen. 

In  connection  with  the  second  standard  relating  to  the  oxygen  bal- 
ance, it  is  expected  that  there  will  be  times  when  a  condition  of  extreme 
refrigeration  will  exist  in  the  waters  of  the  canal  which  may  result  in  a 
five-day  oxygen  demand  value  in  excess  of  the  dissolved  oxygen  content, 
but  it  is  considered  that,  with  an  absence  of  settleable,  putrescible  solids 
in  the  water  and  the  probability  of  the  presence  also  of  an  ample  supply 
of  dissolved  oxygen,  a  violation  of  this  standard  under  these  conditions 


78 


will  not  be  detrimental  to  the  maintenance  of  proper  stream  conditions 
in  the  Illinois  River  below  the  terminus  of  the  Drainage  Canal. 

It  is  also  suggested  in  connection  with  the  application  of  these 
standards  of  permissible  pollution  that  sewage  treatment  devices  should 
not  be  expected  to  register  maximum  efficiency  at  all  times,  and  that 
occasionally  conditions  will  arise  which  will  temporarily  reduce  their 
efficiency  until  proper  corrective  measures  can  be  applied.  Fallibility 
is  characteristic  of  all  things  human,  so  that  these  standards  are  to  be 
considered,  as  a  rule,  with  occasional  justifiable  and  unavoidable  ex- 
ceptions. 


79 


PART  VI. 

REQUIRED  DEGREE  OF  PURIFICATION  WITH 
VARIOUS  DILUTIONS. 

Our  instructions  require  that  we  should  report  upon  the  purifica- 
tion works  necessary  under  each  of  several  diversions  from  Lake  Michi- 
gan;  namely  2,000,  4,167,  6,000,  7,500,  8,500,  and  10,.000  cubic  feet  per 
second. 

We  have  been  instructed  to  consider  these  quantities  as  stated  to  be 
total  diversions  from  the  lake,  including  the  water  contained  in  the  sew- 
age plus  the  water  used  for  diluting  purposes.  Thus  practically  speak- 
ing, the  total  diversion  is  equivalent  to  the  dry  weather  flow  discharged 
at  the  mouth  of  the  Drainage  Canal  near  Lockport. 

Water  for  Dilution: 

For  the  purpose  of  this  study  the  amount  of  water  available  for 
dilution  in  the  critical  period  of  the  year,  July  and  August,  is  considered 
to  be  the  total  diversion  less  the  liquid  volume  of  sewage  of  the  Sanitary 
District.  In  this  computation  it  will  be  assumed  that  the  sewage  liquid 
is  substantially  the  same  as  that  which  was  analyzed  in  determining  the 
total  organic  load  of  the  Sanitary  District  as  summarized  in  Part  IV  of 
this  report. 

In  the  estimates  for  purification  works  hereinafter  made,  the  above 
total  diversions  from  the  lake  are  considered  as  constant  from  year  to 
year.  The  organic  load  of  the  city  as  shown  in  Table  12  of  Part  IV 
must  grow  from  year  to  year.  Experience  indicates  that  during  the  hot 
weather  months  the  sewage  has  been  delivered  at  the  sewer  outlets  in  a 
condition  practically  devoid  of  oxygen.  Within  ordinary  variations  in 
the  supply  of  water  per  capita,  this  will  probably  continue  to  be  the  fact. 
Therefore,  with  a  constant  total  diversion  from  the  lake  and  an  increase 
in  organic  load  which  is  delivered  at  the  sewer  mouths  devoid  of  oxy- 
gen, the  available  diluting  water  will  progressively  decrease  with  the 
growth  of  the  city,  and  the  effectiveness  of  works  for  purification  must 
progressively  increase  as  time  goes  on. 

Organic  Load  and  Dilution: 

The  organic  content  of  sewage  for  practical  purposes  must  be  deter- 
mined at  the  point  of  deHvery  of  the  sewers.  At  this  point  in  warm 
weather  more  or  less  oxidation  has  already  taken  place.    The  analysis 


80 


represents  the  organic  content  of  that  particular  sewage  which  has 
passed  through  a  certain  history  as  regards  amount  of  dilution  and  in 
other  respects.  If  the  water  supply  per  capita  has  been  less,  the  analy- 
sis would  have  shown  a  sewage  somewhat  stronger  in  organic  load  per 
capita,  for  less  oxidation  would  have  taken  place  enroute  to  the  sewer 
outlet.  If  the  water  supply  per  capita  had  been  greater,  the  analysis 
would  have  shown  less  organic  matter  per  capita,  or  more  dissolved 
oxygen  in  the  sewage,  possibly  both. 

It  is  believed  that  when  considering  such  variations  in  the  use  of 
water  per  capita  as  may  occur  in  Chicago,  it  will  be  immaterial  whether 
the  organic  wastes  of  the  city  are  diluted  by  water  taken  into  the  sewers 
through  the  faucet  or  by  water  mixed  with  the  sewage  at  the  sewer  out- 
let. It  is  our  opinion,  therefore,  that  it  will  be  logical  and  proper  to 
take  the  organic  load  of  the  District  at  the  time  when  the  analyses  were 
made ;  to  take  the  liquid  volume  of  the  sewage  existing  at  the  time  when 
the  analyses  were  made ;  to  assume  that  all  sewage  is  delivered  to  the 
stream  devoid  of  oxygen ;  to  assume  that  the  liquid  volume  of  the  sew- 
age will  increase  in  proportion  to  the  increase  in  the  organic  load, 
namely,  that  the  consumption  of  water  per  capita  remains  constant; 
and  that  the  available  diluting  water  will  be  the  total  diversion  less  the 
liquid  sewage  computed  upon  the  basis  as  above. 

The  Sanitary  District  has  made  a  careful  estimate  of  the  total  liquid 
load  as  of  the  year  1920  at  758  million  gallons.  This  is  equivalent  to 
253  gallons  per  capita.  We  have  used  the  round  number  250  gallons 
])er  capita  in  computing  Table  17,  which  shows  the  total  net  dilution 
water  available  between  1925  and  1945  under  the  various  specified  total 
diversions  from  2,000  to  10,000  second  feet.  The  table  also  shows  the 
available  oxygen  in  the  dilution  water.  These  figures  are  used  in  Parts 
XIII,  XIV,  and  XV  of  this  report. 

Necessary  Puri-fication  Plant  Efficimcies : 

In  selecting  the  type  of  treatment  best  adapted  to  supplement  vari- 
ous rates  of  dilution,  it  is  useful  to  estimate  the  average  rate  of  purifi- 
cation that  would  be  required  to  produce  a  satisfactory  effluent.  Upon 
the  following  pages  we  describe  the  method  of  calculation,  and  tabulate 
the  principal  results. 

The  degree  of  purification  of  the  combined  wastes  of  the  Sanitary 
District  of  Chicago  which  must  be  accomplished  in  order  to  make  cer- 
tain specified  diversions  effective  in  maintaining  proper  conditions  in  the 
rivers  which  receive  the  discharge  of  the  Drainage  Canal,  is  determined 
on  the  basis  of  the  daily  oxygen  required  by  the  entire  liquid-borne 
wastes  of  the  District,  and  the  supply  of  oxygen  furnished  daily  by  any 
given  diversion  of  lake  water. 


81 

TABLE  17. 

ESTIMATED  "NET  DILUTION  WATER"  WITH  VARIOUS  "TOTAL 
DIVERSIONS"  AND  OXYGEN  AVAILABLE  FOR  DILUTION 
IN  JULY  AND  AUGUST. 


Year 

1925 

1930 

1935 

1940 

1945 

Estimated  volume  of  sewage  deliv- 

ered to  stream  devoid  of  oxygen — 

1280 

1410 

1530 

1650 

1770 

With  2000  sec.  ft.  Constant  Diversion 

Net  water  for  dilution  sec.  ft  

720 

590 

470 

350 

230 

Available  oxygen  lbs.  per  day. . . . 

31000 

25400 

20200 

15000 

9900 

With  4167  sec.  ft.Constant  Diversion 

2887 

2757 

2637 

2517 

2397 

Available  oxygen  lbs.  per  day. . . . 

124000 

118400 

113200 

108000 

103000 

With  6000  sec.  ft.  Constant  Diversion 

Net  water  for  dilution  sec.  ft  

4720 

4590 

4470 

4350 

4230 

Available  oxygen  lbs.  per  day. . . . 

203000 

197000 

192000 

187000 

182000 

With  7500  sec.  ft.  Constant  Diversion 

6220 

6090 

5970 

5850 

5730 

Available  oxygen  lbs.  per  day. . . . 

268000 

262000 

257000 

252000 

246000 

With  8500 sec.  ft.  Constant  Diversion 

Net  water  for  dilution  sec.  ft  

7220 

7090 

6970 

6850 

6730 

Available  oxygen  lbs.  per  day. . . . 

310000 

305000 

300000 

294500 

289000 

With  10000  sec.  ft.  Constant  Diversion 

Net  water  for  dilution  sec.  ft  

8720 

8590 

8470 

8350 

8230 

Available  oxygen  lbs.  per  day. . . . 

375000 

370000 

365000 

360000 

354000 

The  basic  data  for  the  first  part  of  this  computation  is  recorded  in 
Part  IV,  Table  12,  in  which  is  shown  the  total  oxygen  required  per 
day,  separately  and  collectively,  by  the  three  polluting  elements  con- 
tributing to  the  load.  This  same  table  also  shows  the  total  daily  oxygen 
loads  of  the  entire  district  for  the  year  1925,  and  for  five-year  intervals 
to  1945. 

One  second  foot  of  lake  water  per  day  during  the  warm  months  of 
the  year  (July  and  August)  will  supply  forty-three  pounds  of  oxygen, 
and  the  second  feet  of  lake  water  required  per  day  during  July  and 
August  will  be  as  shown  in  the  first  portion  of  Table  18. 

Taking,  for  instance,  the  second  feet  per  day  required  for  the  year 
1925,  Table  12  of  Part  IV  shows  the  total  daily  oxygen  requiremnt 
on  the  five-day  demand  basis  to  be  856,000  pounds,  consequently,  856- 
000  pounds  divided  by  forty-three  pounds  gives  19,900  as  the  second 
feet  required  per  day  for  untreated  sewage. 

Table  18  shows  the  daily  oxygen  loads  for  the  polluting  unit 
of  each  polluting  element ;  also  the  second  feet  of  water  required  per  day 
during  July  and  August  for  each  polluting  unit.  These  months  were 
selected  for  use  because  they  represent  the  critical  period  of  the  year 
both  as  regards  oxygen  supply  and  demand. 


82 


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240 
7500 
5000 

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Pounds 
Per  Pollul 

CO 

ft 

182 
5650 
3750 

Pounds  Oxygen 
Supplied  During 
July  and  August 
Per  Sec.  Ft.  Per 
Day  by  Diluting 
Water 

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83 


If  it  is  desired  to  determine  the  pounds  of  oxygen  available  in  one 
second  foot  of  lake  water  per  day,  the  result  is  secured  by  multiplying 
as  follows : 

Parts  per  million  of  dissolved  oxygen  in  water  X  0.646  M.  G.  in 
one  second  foot  per  day  X  8.33  pounds  per  gallon,  or  parts  per  million 
of  dissolved  oxygen  in  water  X  5.4. 

The  factor  5.4  is  the  product  of  0.646  X  8.33  and  is  a  constant. 

Table  19  shows  the  second  feet  required  per  day  during  July 
and  August  for  five-year  periods  from  1925  to  1945,  and  for  five,  ten  and 
twenty-day  oxygen  demand  values.  The  five-day  demand  is  sixty-eight 
percent  of  the  twenty-day  demand  and  the  ten-day  demand  is  ninety 
percent  of  the  twenty-day  value.  It  is  assumed  in  this  computation 
that  the  strength  of  the  polluting  unit  of  each  polluting  element  will 
remain  the  same  during  the  period  of  time  involved. 

The  second  section  of  Table  19  shows  the  purification,  expressed 
in  percent,  required  for  gross  diversions  of  2,000,  4,167,  7,500,  8,500 
and  10,000  second  feet  per  day  and  for  oxygen  demand, values  of  five, 
ten  and  twenty  days. 

The  computation  showing  the  percentage  of  purification  required, 
is  simply  one  of  subtraction  and  division,  and  may  be  illustrated  by  tak- 
ing the  first  value  in  the  table ;  viz.,  96.4  which  is  arrived  at  as  follows: 
19,900  second  feet  —  (2,000  second  feet  —1,280  second  feet) 
divided  by  19,900  or  96.4%. 

The  percentage  values  in  this  table  are  carried  to  the  first  place 
beyond  the  decimal ;  however,  this  is  not  intended  to  imply  that  this 
degree  of  refinement  should  be  followed  in  the  use  of  these  values  as 
they  constitute  simply  a  record  of  a  mathematical  computation. 

With  these  data  in  hand  and  a  knowledge  of  practicable  plant  effi- 
ciencies, it  is  possible  to  select  the  types  of  treatment  works  that  would 
produce  required  results. 

Seasonal  Variations: 

All  the  computations  hereinabove  made  refer  to  the  critical  season 
of  the  year,  namely,  the  warm  months  of  July  and  August.  In  the 
winter  time  each  unit  of  lake  water  will  carry  about  double  the  amount 
of  oxygen  available  during  the  critical  period.  Furthermore,  oxidation 
takes  place  at  a  slower  rate  during  the  cooler  months  of  the  year,  and 
the  sewage  is  thus  afforded  the  opportunity  to  travel  further  down- 
stream, to  be  subjected  to  additional  aeration  and  to  be  mixed  with  ad- 
ditional tributary  waters. 

For  all  these  reasons,  it  is  undoubtedly  practicable  to  regulate  the 
diversion  from  the  lake  in  accordance  Vv^ith  the  needs  of  the  situation 


84 


existing  from  month  to  month.  All  the  interests  affected  by  diversion 
of  water  from  the  lake  are  concerned  only  with  an  average  diversion. 
There  appears  to  be  no  reason  why  it  will  not  be  entirely  practicable  to 
materially  increase  the  flows  herein  estimated  for  the  warm  months  of 
the  year  should  occasion  arise,  and  to  save  the  water  thus  taken  during 
other  months  of  the  year,  thus  staying  within  a  stipulated  average 
diversion. 

Factor  of  Safety: 

It  must  be  admitted  that  it  is  not  practicable  to  compute  exactly  the 
amount  of  diluting  water  that  necessarily  must  be  added  to  the  sewage 
in  order  to  obviate  nuisance  and  to  permit  a  thriving  fish  life.  It  is  de- 
sirable that  there  should  be  a  factor  of  safety  to  provide  against  error. 
In  our  opinion,  it  will  be  wise  to  adopt  as  the  average  diversion  with 
various  degrees  of  purification  the  amounts  herein  set  down  as  required 
in  the  months  of  July  and  August,  and  to  use  the  additional  water  avail- 
able in  the  cooler  months  of  the  year  as  a  factor  of  safety,  thus  permit- 
ting some  increase  of  the  dilution  in  the  hot  months  to  cover, 

(a)  The  possibility  of  less  reaeration  in  the  lower  river  than 
herein  contemplated. 

(b)  Washings  from  the  sewers  in  storm  that  may  be  necessarily 
by-passed  from  the  sewage  purification  plants. 

(c)  The  accidental  depletion  in  the  oxygen  in  the  lower  river 
through  the  sudden  death  of  green  plant  growths. 

(d)  Some  degree  of  inferiority  in  the  diluting  water  entering 
through  the  Sag  Canal  and  other  minor  drafts  on  the  oxygen  supply  not 
specifically  considered  herein. 

Additional  Oxygen: 

No  specific  consideration  has  been  given  to  additional  oxygen  that 
may  be  furnished  by  the  effluent  from  the  sprinkling  filter  plants  and  the 
activated  sludge  plants.  This  oxygen  will  be  in  addition  to  that  ob- 
tained from  the  lake  and  from  the  other  sources  mentioned. 

At  the  present  time  practically  no  aeration  is  obtained  at  Lockport 
in  dropping  the  water  from  the  Drainage  Canal  into  the  Des  Plaines 
River  in  passing  through  the  water  wheels.  It  would  probably  be  pos- 
sible to  add  from  one  to  two  parts  per  million  to  the  sewage  by  an  over- 
fall especially  designed  for  aeration.  This  possibility  will  occur  at  all 
of  the  dams  hereinafter  constructed  for  navigation  purposes  on  the 
Illinois  River  except  where  the  water  may  be  used  for  power  purposes. 


85 


PART  VII. 

PROTECTION  OF  THE  WATER  SUPPLY 

It  must  be  a  part  of  any  scheme  for  sewage  disposal  that  the  water 
supply  should  be  protected  against  any  possibility  of  sewage  contamina- 
tion. Unless  this  is  accomplished  sewage  disposal  fails  in  its  principal 
requirement. 

This  matter  is  particularly  important  to  municipalities  located  on 
the  shores  of  the  Great  Lakes.  In  all  of  these  cities  the  lakes  constitute 
the  only  practicable  means  for  municipal  water  supply.  In  many  in- 
stances the  lakes  are  the  only  practicable  means  for  sewage  discharge. 

In  the  Chicago  region  the  means  has  been  provided  through  the 
drainage  canal,  by  which  the  great  majority  of  all  impurities  are  divert- 
ed from  Lake  Michigan.  As  will  be  pointed  out,  certain  sources  of  pol- 
lution still  remain,  and  will  continue  to  exist,  regardless  of  any  improve- 
ments in  the  Sanitary  canal.  These  sources  of  pollution  are  sufficiently 
great  to  seriously  menace  the  water  supply,  unless  adequate  precautions 
are  taken  to  guard  against  them. 

Lake  Shore  Line: 

The  south  end  of  Lake  Michigan  is  relatively  shallow.  On  the  Chi- 
cago water  front  the  distance  outward  for  twenty-five  feet  depth  varies 
generally  from  half  a  mile  to  a  mile.  The  four-mile  crib  at  Chicago 
stands  in  thirty-six  feet  of  water.  The  depth  of  water  is  five  to  eight 
feet  less  at  the  other  intake  cribs,  located  at  lesser  distances  from  shore. 
Opposite  the  mouth  of  the  Chicago  River  a  depth  of  fifty  feet  is  attained 
only  at  seven  miles  from  the  shore.  Opposite  the  mouth  of  the  Calumet 
River  the  same  depth  is  only  attained  nine  miles  out.  Opposite  Gary 
the  lake  is  deeper ;  fifty  feet  is  attained  at  a  distance  of  four  miles  from 
shore. 

At  the  shore  line  there  is  a  fringe  of  sand  generally  varying  from 
ten  feet  more  or  less,  at  Chicago,  to  about  fifty  feet  in  the  vicinity  of 
Gary.  This  sand  is  a  superficial  deposit  upon  a  bed  of  blue  clay.  The 
sand  layer  generally  disappears  within  a  mile  or  two  from  shore,  and 
the  coating  is  scattering  and  thin  at  this  distance  out. 

Intakes  and  Pollution  Sources: 

The  accompanying  map,  Figure  1,  shows  the  Lake  Michigan  shore 
line,  the  location  of  the  Water  Works  intakes,  and  the  location  of  the 
streams  forming  potential  sources  of  pollution. 


The  distance  of  the  Chicago  Water  Works'  cribs  from  the  mouth 
of  the  Chicago  River,  and  Calum.et  River  respectively  are  as  follows : 


Miles  from  Chicago 
River  Mouth. 


Miles  from  Calumet 
River  Mouth 


Wilson  Ave.  Crib  

Carter  Harrison  Crib  

Chicago  Ave.  Crib  

Four  Mile  Crib  

Hyde  Park  &  E.  F.  Dunn  Cribs 


5.2 

2.3 

1.3 

3 

8 


16 
12.7 
12.2 
9.3 
3.7 


About  six  miles  southeast  of  the  Calumet  River  mouth,  the  Indiana 
Harbor  canal  is  located,  which  taps  the  Grand  Calumet  River  and  dis- 
charges more  or  less  sewage  into  the  lake.  Between  these  two  points 
lie  the  Water  Works'  intakes  of  Whiting  and  Hammond,  Indiana.  The 
East  Chicago  intake  is  close  to  the  shore,  and  only  a  short  distance  from 
the  Indiana  Harbor  canal.  The  Gary  intake  is  one  and  one-half  miles 
from  shore,  six  miles  east  of  the  Indiana  Harbor  canal  and  twelve  miles 
from  the  Calumet  River,  measured  in  a  direct  line. 

Sources  of  Pollution: . 

From  the  mouth  of  the  Calumet  River,  north  to  the  Cook  County 
line,  the  sewers  are  now  diverted  from  the  lake.  North  of  the  Cook 
County  line  the  towns  between  Highland  Park  and  Waukegan  sewer 
into  the  lake,  except  a  small  population  in  Highland  Park  which  sewers 
inland  toward  the  Skokie  Marsh.  Most  of  this  sewage  reaches  the 
lake  in  a  raw  state  at  present.  A  portion  of  it  is  partially  purified. 
These  cities  are  members  of  the  North  Shore  Sanitary  District,  intended 
to  prevent  excessive  pollution  of  the  lake.  Conditions  in  this  locality 
will  probably  be  somewhat  improved  hereafter. 

Indiana  Towns: 

The  Indiana  towns  from  the  State  line  eastward,  including  Gary, 
now  contain  a  population  of  180,000.  These  towns  are  growing  very 
rapidly.  They  are  the  sites  of  some  of  the  largest  industries  in  the 
Chicago  region.  Grand  Calumet  River  is  the  main  sewer  of  this  region. 
Considerable  sewage  from  the  shore  population  in  Hammond  and  Whit- 
ing, and  from  several  industries,  discharges  directly  to  the  lake.  The 
entire  City  of  Gary,  and  the  greater  part  of  the  sewage  in  East  Chicago 
and  Hammond  drains  inland  and  only  reaches  the  lake  through  the  out- 
lets of  the  Calumet. 

Calumet  River: 

Attention  is  invited  to  the  Grand  Calumet  and  Little  Calumet 
Rivers,  and  their  relation  to  Lake  Calumet,  the  outlet  of  the  two  streams 
into  Lake  Michigan,  and  the  location  of  the  Calumet  Sag  Channel.  The 


87 


Sag  Channel  is  now  designed  for  2,000  second  feet.  At  certain  seasons 
of  the  year  this  is  sufficient  to  take  the  sewage  of  the  Chicago  Sanitary 
District  reaching  it  and  the  entire  flows  of  the  Grand  and  Little  Calumet 
Rivers.  In  seasons  of  flood  the  Sag  Channel  is  very  insufficient  to  take 
the  flow  of  these  streams. 

Figure  17  is  a  watershed  map  of  the  Grand  Calumet  and  Little 
Calumet  Rivers.  The  total  drainage  area  of  these  streams  is  770  square 
miles. 

The  maximum  measured  flood  in  this  district  occurred  in  February, 
1887.  It  was  measured  at  Riverdale  on  the  Little  Calumet  River  and 
amounted  to  13,300  second  feet.  The  Sanitary  District  of  Chicago  has 
estimated  the  maximum  flood  to  be  expected  from  the  combined  Grand 
and  Little  Calumet  Rivers  at  16,000  second  feet.  The  estimate  of  the 
International  Waterways  Commission  is  substantially  the  same. 

Continuous  gaugings  are  not  available  showing  the  frequency  and 
duration  of  floods.  In  a  report  of  Mr.  Wisner,  Chief  Engineer,  of  the 
Chicago  Sanitary  District,  June  9,  1909,  it  is  estimated  that  with  2,000 
second  feet  flowing  in  the  canal,  there  would  be  22.4  days  per  year  when 
the  flood  flow  from  the  Calumet  Rivers  would  exceed  the  flow  of  the 
Sag  canal.  The  source  of  the  information  upon  which  this  estimate  is 
based  is  not  stated.  Judging  by  the  experience  of  the  nearest  adjoining 
streams  upon  which  flow  records  are  available,  it  appears  that  the  above 
figure  may  be  approximately  true.  Flow  records  on  the  Kalamazoo 
River,  draining  somewhat  similar  territory  in  Michigan,  applied  to  the 
Calumet  Rivers  with  drainage  area  correction,  indicate  a  probabihty  of 
eighteen  days  per  year  when  the  flow  of  these  screams  might  be  expected 
to  exceed  2,000  second  feet.  A  similar  comparison  based  on  daily  gaug- 
ings on  the  Des  Plaines  River,  corrected  for  drainage  area,  indicate 
about  twenty-five  days  flow  in  excess  of  2,000  second  feet. 

A  large  flood  on  these  streams  will  undoubtedly  wash  great  quanti- 
ties of  filth  into  Lake  Michigan.  The  Calumet  cities  are  beginning  to 
study  the  question  of  sewage  purification.  Conditions  in  the  future  will 
no  doubt  be  improved.  No  practicable  means  for  sewage  purification 
will  place  these  streams  in  condition  where  their  waters  may  be  period- 
ically flushed  into  the  water  supply  of  the  region  even  occasionally,  with 
safety  to  the  water  supplies. 

Water  Level  Changes: 

The  lower  Calumet  River,  between  Calumet  Lake  and  Lake  Michi- 
gan, is  dredged  200  feet  wide  and  twenty-one  feet  deep.  It  requires  a 
slope  of  only  a  small  fraction  of  an  inch  from  Lake  Calumet  to  Lake 
Michigan  to  discharge  1,000  second  feet.  A  difference  in  level  of  slightly 
over  two  inches  will  discharge  5,000  second  feet.   A  recording  guage  at 


88 


89 


the  mouth  of  the  Cahimet  River  shows  that  the  surface  of  the  lake  is 
constantly  rising  and  falling,  due  principally  to  changes  in  direction  and 
velocity  of  the  wind.  Changes  of  six  inches  in  less  than  an  hour  are 
very  common.  It  is  an  exceptional  day  in  which  the  total  variation  is 
less  than  six  inches  at  different  times  during  the  day.  Upon  moderately 
windy  days  the  variation  is  frequently  more  than  one  foot. 

Some  years  ago  we  conducted  a  systematic  watch  of  the  currents  in 
the  lower  Calumet  River,  estimating  the  current  velocities  by  rod  floats 
This  study  confirmed  what  would  be  expected  by  the  water  level  varia- 
tions in  Lake  Michigan,  and  the  comparatively  large  volume  of  stagnant 
water  in  the  Calumet  Rivers  and  Lake  Calumet.  Whenever  the  lake 
surface  dropped  a  few  inches  a  rapid  current  was  set  up  toward  Lake 
Michigan,  which  continued  until  a  change  in  the  wind  caused  the  lake 
surface  to  rise,  in  which  case  if  the  rise  was  great  enough  the  outflow 
was  stopped,  the  current  reversed,  and  often  a  rapid  current  ran  inland 
for  several  hours,  to  return  again  with  a  subsequent  fall  in  the  lake  level. 
Thus  on  February  20,  1920,  with  a  variation  in  lake  level  of  about  three 
tenths  of  a  foot  and  a  brisk  northwest  wind  gradually  decreasing  after 
3  p.  m.,  the  flow  of  the  river  varied  from  1,000  second  feet  from  the  lake 
at  2  p.  m.  to  3,000  second  feet  toward  the  lake  at  5  p.  m. 

On  February  11th,  with  a  brisk  northeast  wind,  the  flow  from  1  - 
to  5  p.  m.  varied  from  1,000  to  1,500  second  feet  landward.  For  short 
periods  it  became  nearly  stagnant.  On  February  12th  with  a  mild 
southwest  wind  the  flow  averaged  about  2,000  second  feet  toward  Lake 
Michigan  from  1  to  3  p.  m.,  but  stopped  entirely  as  the  wind  died  down 
about  4  p.  m. 

Thus  the  Calumet  Rivers  and  Lake  are  constantly  ''breathing"  in 
and  out,  toward  and  from  Lake  Michigan,  depending  principally  upon 
the  direction  and  velocity  of  the  winds.  In  severe  storms  there  are  also 
very  important  barometric  changes  causing  lake  level  fluctuations  of 
several  feet,  bringing  out  heavy  discharges  for  periods  of  many  hours. 

No  doubt  a  similar  condition  exists  where  the  Indiana  Harbor 
canal  taps  the  Grand  Calumet  River.  This  is  a  wide  and  deep  harbor ; 
only  a  small  difference  in  head,  an  inch  or  less,  is  required  for  the  inter- 
change of  water  between  the  river  and  Lake  Michigan.  The  sewage  of 
Gary  is  supplemented  by  a  large  amount  of  condensing  water  from  the 
steel  mills.  A  rapid  flow  is  produced  in  the  upper  Grand  Calumet.  The 
final  disposition  of  this  sewage  laden  water  depends  upon  the  stream 
cross-sections,  and  the  relative  elevations  of  the  moment  as  between  the 
Calumet  Rivers  and  Lake  Michigan. 


90 


Chance  Pollution  from  Chicago  River: 

Prior  to  the  construction  of  the  drainage  canal,  conditions  at  the 
mouth  of  the  Chicago  River  were  somewhat  similar  to  those  previously 
described  as  prevailing"  in  the  Calumet  region.  The  floods  of  the  Chi- 
cago River  have  not  been  accurately  measured.  It  has  been  estimated 
that  the  discharge  capacity  of  the  storm  water  sewers  in  Chicago  makes 
it  possible  to  produce  a  flood  of  about  11,000  second  feet.  Possibly  it 
may  be  questioned  whether  this  is  so  at  the  present  time.  If  it  is  not 
true  today  it  probably  will  be  true  as  the  city  becomes  improved  to  a 
greater  extent  than  at  present.  With  the  drainage  canal  in  operation  at 
the  rates  of  flow,  which  have  prevailed  during  the  past  ten  years,  there 
is  little  danger  of  a  material  amount  of  flood  water  reaching  Lake  Michi- 
gan. There  have  been  a  few  occasions,  however,  for  a  short  time  when 
a  lakeward  flow  has  been  noticed  following  great  rain  storms.  With 
lesser  flows  in  the  drainage  canal  these  occasions  would  become  more 
frequent  and  of  longer  duration. 

At  the  present  time  lakeward  flows  of  water  would  be  very  detri- 
mental to  the  Chicago  water  supply.  With  the  general  adoption  of 
sewage  purification  works,  and  the  consequent  cleaning  up  of  the  Chi- 
cago River,  the  dangers  resulting  from  a  lakeward  flow  of  water  would 
be  diminished  but  there  would  still  be  a  potential  danger  to  the  water 
supply.  The  purification  of  the  sewage  would  not  be  a  determining  fac- 
tor in  the  matter  further  than  to  diminish  the  quantity  of  filth  that  might 
be  washed  into  the  lake  by  flow  reversal. 

Travel  of  Pollution  in  the  Lake:  _ 

The  question  as  to  the  travel  of  pollution  in  the  waters  of  Lake 
Michigan  has  been  studied  very  thoroughly  upon  several  occasions  cov- 
ering the  Chicago  water  front,  the  water  front  opposite  the  Chicago 
north  shore  suburban  towns  aixl  further  north  along  the  lake  at  Racine 
and  Milwaukee.  The  results  of  these  studies  indicate  similar  conditions 
wherever  sewage  contamination  reaches  the  lake  and  variable  winds  and 
waves  are  available  for  dispersion.  The  net  results  from  these  studies 
are  well  summed  up  by  Major  W.  V.  Judson  in  his  paper  on  currents 
in  Lake  Michigan,  (first  report  Lake  Michigan  Water  Commission, 
page  67). 

"In  my  opinion  the  currents  of  Lake  Michigan  are  so  irregular  in  char- 
acter that  nothing  would  be  gained  worth  the  cost  if  attempt  were  made  to 
obtain  classified  further  data  of  a  general  nature.  If  it  is  a  question  of  pro- 
tecting the  water  supply  of  any  particular  locality,  in  any  event,  special 
study  would  have  to  be  made  inasmuch  as  the  lake  currents,  available  as  they 
are,  are  much  influenced  by  local  conditions. 


91 


We  do  know,  and  perhaps  it  is  enough  for  the  purposes  of  this  commis- 
sion, that  occasional  currents  of  considerable  velocity,  say  several  miles  per 
hour,  may  be  expected  to  arrive  from  almost  any  direction  at  any  point 
reasonably  near  either  shore  of  the  lake.  It  is,  therefore,  apparent  that  in  a 
general  case  if  the  waters  of  the  lake  are  polluted  by  the  discharge  into  it 
of  large  quantities  of  sewage,  then,  practical  localities  in  the  lake,  even 
twenty  or  thirty  miles  distant  from  the  point  of  entrance  to  the  sewage,  are 
not  safe  places  in  which  to  derive  water  for  domestic  use." 

Numerous  special  investigations  of  lake  water  condition,  and  the 
practical  experience  in  the  operation  of  the  water  works  intakes,  all 
indicate  that  in  any  particular  place  reasonably  adjacent  to  the  lake 
shore  the  quality  of  the  water  varies  between  extremely  wide  limits,  in- 
cluding water  almost  sterile  for  considerable  periods  of  time,  the  usual 
prevalence  of  moderately  heavy  pollution,  depending  upon  the  locality, 
with  occasional  gross  pollutions,  regardless  of  locality  within  practicable 
reach  of  a  water  works  inlet. 

Turbidity: 

In  drawing  a  continuous  supply  for  the  wrater  works,  it  is  necessary 
to  locate  the  intake  not  closer  than  two  or  three  thousand  feet  from  the 
shore,  in  order  to  prevent  ingress  of  sand  and  stoppages  from  anchor 
ice.  A  large  supply  must  necessarily  be  taken  further  from  the  shore. 
The  Chicago  intakes  are  located  from  two  to  four  miles  outward. 

Upon  the  west  shore  of  Lake  Michigan  there  are  long  periods  of 
the  summer  season  when  the  prevaihng  winds  are  from  the  west  and 
southwest.  At  such  times  the  surface  water  is  blown  out  into  the  lake 
and  is  replaced  by  a  return  current  along  the  lake  bottom.  At  such 
times  as  this  an  exceptionally  clear  and  pure  water  may  be  drawn  from 
an  intake  located  at  or  below  mid  depth,  in  twenty-five  to  forty  feet 
depth. 

Severe  storms  usually  occur  with  an  east  or  northeast  wind,  The 
surface  water  is  blown  in  toward  the  shore,  breakers  are  formed  in  the 
shallow  water,  the  dirty  sand  and  accumulated  sludge  adjoining  the 
shore  are  stirred  up  and  the  water  is  returned  lakeward  as  an  undertow. 
The  filth  is,  however,  more  or  less  intermixed,  from  bottom  to  top  of 
water,  in  depths  under  fifty  feet.  At  such  times  as  this  no  clean  or  pure 
water  can  be  obtained ;  the  degree  of  the  turbidity  and  extent  of  pol- 
lution depends  principally  upon  the  severity  of  the  storm  and  somewhat 
upon  its  direction. 

Wind  conditions  varying  between  the  two  extremes,  which  have 
been  mentioned  above,  produce  water  conditions  varying  between  the 
extremes  of  quality  previously  mentioned.  There  are  certain  conditions 
in  storms  when  pollution  may  travel  with  great  rapidity  to  a  Water 


92 


Works  intake.  The  situation  is  much  like  the  dissipation  of  smoke 
from  a  tall  chimney.  In  relatively  calm  weather  it  may  disappear  within 
a  short  distance  from  the  chimney.  Under  a  current  of  wind  it  may 
stream  out  in  one  direction,  traveling  for  miles.  Pollution  in  a  lake  may 
travel  in  similar  manner. 

Present  Condition  of  the  Water  Supply: 

About  two-thirds  of  the  time  the  water  drawn  from  the  Chicago 
cribs  is  clear.  It  is  often  quite  pure  for  short  periods.  However,  its 
sanitary  character  cannot  be  depended  upon  from  hour  to  hour.  For  a 
considerable  portion  of  time  at  all  the  intake  cribs  it  is  distinctly  bad. 
It  can  only  be  safely  used  after  heavy  doses  of  liquid  chlorine.  The  re- 
quired dosage  has  increased  of  recent  years.  Occasionally  the  Health 
Department  has  advocated  boiling.  The  water  as  delivered  to  con- 
sumers is  often  decidely  turbid  for  weeks  at  a  time. 

The  net  result  from  a  sanitary  standpoint  from  the  water  as  chlor- 
inated has  been  very  good,  although  there  have  been  times  when  it  has 
been  suspected  of  producing  typhoid  fever  in  local  instances,  apparently 
due  to  chance  pollution.  To  a  large  number  of  people  the  taste  imparted 
to  the  water  through  the  chlorine  dosage  is  extremely  objectionable. 
The  demand  is  becoming  stronger  from  year  to  year  for  a  water  free 
from  the  chlorine  taste. 

Records  of  Turbidity: 

The  two  mile  crib  supplying  the  Chicago  Avenue  pumping  station 
and  a  part  of  the  water  of  the  22nd  St.  Station  furnishes  about  one-fifth 
of  the  total  water  supply  of  the  city,  including  the  downtown  district. 
Table  20  shows  the  prevailing  turbidity  of  the  water  drawn  from  this 
crib  during  the  past  ten  years. 

In  the  consideration  of  turbidity,  which  represents  the  apparent 
cleanliness  of  the  water,  it  should  be  stated  that  a  clean  water,  such  as 
produced  by  water  filtration  plants,  has  a  turbidity  of  about  five.  A 
turbidity  of  ten  is  noticeable  by  people  accustomed  to  clear  water.  A 
turbidity  of  fifteen  would  cause  serious  complaint  where  people  are 
accustomed  to  clear  water.  A  turbidity  of  fifty  represents  a  very  dirty 
water  that  would  desirably  be  treated  by  sedimentation  before  applica- 
tion to  a  mechanical  filter. 

The  records  for  the  two  mile  crib  shows  that  the  water  has  a  tur- 
bidity more  than  ten  practically  at  all  times.  It  has  a  turbidity  above 
fifty  for  periods  totaling  from  two  to  seven  weeks  per  year,  excepting 
one  year.  This  crib  being  the  nearest  to  shore  generally  has  the  highest 
turbidity  as  compared  to  other  Chicago  cribs. 


93 


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Table  21  shows  the  maximum  and  average*turbidities  at  each  of  the 
ChicagT  cribs.  The  average  turbidity  was  less  than  ten  a  little  more 
than  haii  the  time  during  the  year  1924,  up  to  October.  The  average 
turbidity  at  all  the  cribs  ranged  between  twenty  and  thirty-five  during 
February,  thirteen  to  twenty-five  during  March,  and  ten  to  fifteen  dur- 
ing April.  The  maximum  turbidity  was  above  ten  at  most  of  the  cribs 
during  the  months  of  February  to  October  inclusive.  It  was  above 
fifty  at  all  the  cribs  during  February,  from  30  to  55  during  March,  from 
eighteen  to  fifty  during  April,  and  ten  to  forty  in  May. 

Filtration: 

All  objection  to  the  piesent  water  supply  can  be  eliminated  by 
mechanical  filtration,  which  it  is  practical  to  apply  to  the  Chicago  watc; 
supply  at  a  comparatively  moderate  expense.  Filtration  will  give  the 
citizens  of  Chicago  pure  clean  water  all  the  time,  eliminating  all  possi- 
bility of  danger  from  the  chance  pollutions  of  the  lake.  A  number  of 
cities  upon  the  Great  Lakes  have  already  installed  filtration  works,  in- 
cluding several  of  the  srnaller  cities  in  the  Chicago  region,  also  including 
the  cities  of  Detroit,  Cleveland,  Lorain,  Erie  and  Niagara  Falls.  In 
several  cases  highly  polluted  waters  are  rendered  entirely  satisfactory 
for  domestic  consumption. 

Polluted  Waters  Treated: 

At  several  places,  on  the  Great  Lakes,  lake  water  is  safely  filtered 
after  receiving  the  sewage  of  the  city  supplied  through  intakes  removed 
only  a  comparatively  short  distance  from  the  sewage  outlets.  Cleveland 
is  an  example  of  this  type.  At  Cleveland  the  water  is  taken  within 
19,000  feet  from  sewer  inlets  receiving  only  partially  purified  sewage. 

Upon  the  Ohio  River,  city  after  city,  from  Pittsburgh  to  Cairo,  takes 
its  water  supply  from  the  river,  returning  the  sewage  again  to  the 
stream,  the  water  being  again  and  again  used  by  the  cities  downstream 
after  filtration.  Table  22  shows  a  list  of  these  cities  with  approximate 
distances  measured  by  river,  from  sewage  outlet  to  water  works  intake. 

Although  it  has  been  felt  desirable,  and  is  proper  in  all  cases  in  the 
water  supply  of  cities,  to  select  ^mre  a  source  as  possible  even  when 
filtration  is  resorted  to,  it  has  been  necessary  in  some  cases  to  filter  more 
or  less  grossly  polluted  water.  The  results  from  the  sanitary  stand- 
point can  safely  be  said  to  have  exceeded  expectations  wherever  filtra- 
tion has  been  resorted  to. 


97 


TABLE  22. 


SUCCESSIVE  POLLUTION   AND  USE  FOR  WATER  SUPPLY  OF  THE 
OHIO  RIVER  FROM  PITTSBURGH  TO  CAIRO. 


City  Using  Filtered  River  Water 
Miles 

Below  Popu- 
Pitts-  lation 
burgh    City  1920 
0    Pittsburgh   588.343 

50    E.  Liverpool    21,411 

66  Toronto    4,684 

80  Steubenville    28,508 

105  Wheeling    56,208 

110  Bellaire    15,061 

190  Marietta    15,140 

202  Parkersburg    20,050 

322  Huntington    50,177 

340  Ashland    14,729 

344  Ironton    14,007 

372  Portsmouth,   33,011 

498  Cincinnati   401,247 

499  Newport    29,317 

520  Aurora    4,299 

534  Louisville  234,891 

539  New  Albany    22,992 

B04  Evansville    85,264 

^15  Henderson    12,169 

?37  Mt.  Vernon    5,284 

934    Paducah    24,735 

979    Cairo    15,203 


Nearest  Principal  Source  of  Pollution 
Miles  Popu- 
Up-  lation 
stream    City  1920 


! Beaver  ) 
Monaca  [  ''''' 

20  Wellsville    8,849 

8  Toronto    4,864 

25  Steubenville    28,508 

5  Wheeling    56,208 

73  Moundsville    10,669 

12  Marietta    15,140 

37  Gallipolis    6,070 

4  Catlettsburg    4,183 

4  Ashland    14,729 

28  Ironton    14,007 

126  Portsmouth    33,011 

126  Portsmouth    33,011 

22  Cincinnati   594,000* 

136  Cincinnati   594,000* 

5  Jeffersonville    10,098 

35  Owensboro    17,424 

11  Evansville    85,264 

25  Henderson    12,169 

105  Henderson    12,169 

130  Evansville    85,264 

45  Paducah   24,735 


*Including  adjoining  river  towns. 


Niagara  Falls: 

A  typical  example  as  to  whd.t  filtration  can  accomplish  with  a 
freshly  polluted  water  is  instanced  by  the  experience  at  Niagara  Falls, 
New  York.  For  many  years  prior  to  1913  this  city  was  one  of  the  most 
important  typhoid  centers  in  the  U  !:tcd  States.  The  city  water  supply 
is  taken  from  Niagara  River  a  few  hours  after  the  water  receives  the 
sewage  from  more  than  500,000  people  at  Buffalo,  and  from  other 
smaller  cities  downstream.  The  accompanying  Table  23  shows  the 
typhoid  history  of  Niagara  Falls  prior  to  and  following  the  installation 
of  filter  plants  in  the  year  1913.  Two  plants  were  installed.  The 
municipal  plant  went  into  service  in  February  and  the  New  York  Water 
Company's  plant  went  into  service  in  June,  1913.   For  a  period  of  eigh- 


98 


teen  months  shortly  following  the  installation  of  the  filters  no  typhoid 
deaths  occurred  in  the  city,  although  shortly  prior  thereto  and  for  many 
years  previous  the  typhoid  death  rate  had  commonly  exceeded  100  per 
hundred  thousand  per  annum.  Within  the  past  ten  (10)  years  there 
have  been  only  a  few  cases  reported,  a  careful  tally  of  them  has  been 
kept,  and  it  is  stated  they  have  not  been  traced  to  water  supply. 

Cost  of  Filtration  for  Chicago: 

It  is  believed  that  the  most  feasible  plan  for  filtering  the  Chicago 
water  supply  will  consist  of  plants  located  on  the  lines  of  the  intake 
channels  at  or  close  to  the  Lake  Shore  line.  The  city  could  be  served  by 
four  (4)  plants,  namely  at  Wilson  Avenue,  Chicago  Avenue,  Roosevelt 
Road  and  67th  St.    It  would  be  practicable  to  install  bulkheads  and 

TABLE  23. 

TYPHOID  DEATH  RATE  AT  CITY  OF  NIAGARA  FALLS,  N.  Y. 


Remarks 


Typhoid 

Typhoid 

Estimated 

Death  Rate 

Year 

Deaths 

Population 

per  100,000 

1899 

24 

17,261 

139 

1900 

24 

19,457* 

123 

1901 

29 

20,362 

143 

1902 

22 

21,267 

103 

1903 

29 

22,172 

131 

1904 

34 

25,037 

135 

1905 

49 

26,432 

185 

1906 

43 

27,827 

154 

1907 

37 

28,000 

132 

1908 

28 

29,000 

97 

1909 

24 

29,793 

80 

1910 

32 

30,445* 

105 

1911 

55 

32,800 

168 

1912 

23 

35,000 

66 

1913 

10 

37,000 

27  B( 

1914 

3 

39,000 

7.7 

1915 

0 

41,000 

0 

1916 

5 

43,000 

11.6 

1917 

5 

44,800 

11.1 

1918 

2 

46,600 

4.3 

1919 

2 

48,500 

4.1 

1920 

5 

50,760* 

9.8 

1921 

5 

52,600 

9.5 

1922 

2 

54,800 

3.6 

1923 

1 

57,000 

1.8 

1924 

3 

59,000 

5.1 

Began  water  filtration** 


*U.  S.  Census. 

**Municipal  Water  Filtration  Plant  put  in  operation  in  February. 
**Westem  New  York  Co.  Filtration  Plant  put  in  operation  in  June. 


99 


gates  in  the  tunnels,  pump  the  water  to  the  surface,  pass  it  through 
sedimentation  basins  and  filters,  store  it  in  clear  water  reservoirs  of 
moderate  size,  and  return  the  water  again  to  the  tunnel  system  beyond 
the  shore  gates  where  it  could  pass  as  at  present  to  the  pumping  stations. 

It  is  stated  that  the  water  in  the  tunnel  system  now  receives  some 
pollution  from  unknown  sources  after  entering  the  tunnels.  The  City 
Engineer  states  that  his  investigations  indicate  that  this  pollution  is 
probably  confined  to  pollution  at  certain  shafts.  It  seems  hardly  possible 
that  pollution  could  enter  the  tunnels  proper,  after  passing  landward 
from  the  shore  line.  It  is  feasible  to  stop  the  surface  pollution  at  the 
shafts,  if  it  exists.  It  is  further  possible  in  the  design  of  the  filter 
w^orks  to  eliminate  any  possibility  of  pollution  by  adopting  an  hydraulic 
grade  line  in  the  tunnel  system  above  the  ground  water  plane.  This 
would  be  possible  by  extending  the  shafts  at  the  pumping  stations  to  a 
higher  elevation  and  pumping  water  to  a  corresponding  height  at  the 
shore  line.  This  could  be  done  without  increased  cost  of  pumping.  It 
is  practicable  to  purchase  low  lift  pumps  in  large  units  that  will  have 
an  efficiency  substantially  equal  to  the  pumps  used  in  delivering  water  to 
the  city,  and  there  would  be  no  net  loss  of  head. 

In  several  instances  the  filtration  plants  could  be  located  in  existing 
city  parks,  or  in  connection  with  the  lake  shore  park  improvements  now 
under  way.  It  is  possible  to  design  the  plants  so  that  they  would  add 
materially  to  the  beauty  and  interest  of  the  parks.  Where  the  lake 
shore  is  not  proposed  to  be  used  for  park  purposes,  it  is  possible  to  con- 
struct the  plants  upon  made  ground  closely  adjoining  the  shore  line. 
Much  ground  of  this  character  has  already  been  made  adjacent  to  the 
city,  and  is  in  process  of  making  in  connection  with  Chicago's  lake  front 
improvements. 

Tentative  estimates  made  by  City  Engineer,  John  Ericson,  on  the 
filtration  of  Chicago  water  are  as  follows : 


Total  annual 

Q.^jg  Annual      expense  in- 

*        ■    Investment    Operating  eluding  5%  in- 
perudy  Expenses  terest  and  2% 

depreciation 

Wilson  Ave.  Plant   200       $  4,000,000       $     234,335       $  514,335 

Chicago  Ave.  Plant   500        10,000,000  676,705  1,376,705 

Roosevelt  Rd.  Plant   155  3,100,000  188,120  405,120 

eSth  St.  Plant   445  8,900,000  651,000  1,274,000 


Totals    1,300       $26,000,000       $  1,750,160       $  3,570,160 


The  above  estimate  covers  an  installation  that  would  be  sufficient 
to  filter  the  present  water  supply.  If  the  water  supply  of  the  city  is 
metered,  the  above  plant  would  serve  all  requirements  of  the  city  until 


100 


after  the  year  1960,  making  due  allowance  for  the  seasonal  and  hourly 
variations  in  pumping. 

The  above  total  cost  is  approximately  $8.65  per  capita  on  the  pres- 
ent population  of  Chicago.  The  average  annual  cost,  including  opera- 
ting and  fixed  charges,  is  approximately  $1.20  per  capita  on  the  present 
population,  and  would  be  materially  less  under  the  increased  population 
of  Chicago  during  the  next  thirty  years  during  which  the  investment 
would  be  effective. 

Conclusion  Regarding  Filtration: 

Chicago  is  entitled  to  a  clean  water,  safe  from  a  Sanitary  stand- 
point 365  days  per  year.  This  standard  is  generally  demanded  through- 
out the  United  States.  It  is  only  a  question  of  time  when  it  will  be 
demanded  in  Chicago. 

In  our  opinion  filtration  will  insure  a  pure  clean  water  for  Chicago 
at  all  times,  under  any  diversion  through  the  drainage  canal  exceeding 
2,000  second  feet.  It  is  our  belief  that  no  amount  of  diversion  up  to  the 
present  capacity  of  the  Chicago  drainage  canal  will  insure  safe  water 
for  Chicago  without  filtration.  We  believe  this  is  true  regardless  of 
any  practicable  measures  that  may  be  taken  for  sewage  purification. 
We  believe  it  is  the  only  adequate  safeguard  for  the  Chicago  water 
supply. 


101 


PART  VIII. 

SAVINGS  EFFECTED  BY  METERING. 

The  quantity  of  municipal  sewage  is  largely  dependent  upon  the 
water  supply.  In  Chicago  where  the  population  for  which  sewage  treat- 
ment is  to  be  provided  is  large,  the  industrial  load  is  great,  and  the 
amount  of  water  pumped  is  extravagant,  the  problem  of  keeping  expen- 
ditures for  sewage  treatment  works  reasonably  low,  is  difficult.  The 
first  two  factors,  i.  e.,  population  and  industrial  wastes,  are  fixed  as  of 
any  particular  time ;  the  last  factor,  water  pumpage,  is  capable  of  regu- 
lation. The  question  of  water  waste  restriction  is  acordingly  a  sewage 
disposal  problem  as  well  as  a  water  supply  problem.  With  this  in  mind 
a  study  of  the  effect  of  metering  on  the  costs  of  sewers  and  sewage  dis- 
posal has  been  made  herein  and  incidental  thereto  certain  observations 
as  to  the  effect  upon  the  water  works  and  water  service  are  included. 

At  the  present  time  ninety  percent  of  all  of  the  consumers  furnished 
water  by  the  Chicago  Water  Works  are  served  through  socalled  ''flat 
rates"  under  which  there  is  no  incentive  to  keep  plumbing  in  repair,  nor 
to  curtail  other  wastes.  As  a  result  the  pumpage  of  water  is  excessive, 
the  water  service  is  deficient  as  to  quantity,  qualify  and  pressures,  and 
the  Water  Department  is  confronted  with  the  continual  necessity  of 
making  large  expenditures  in  its  hopeless  effort  to  keep  pace  with  the 
open  faucet. 

In  1923,  the  last  year  for  which  published  records  are  available,  but 
9.65  percent  of  all  services  were  metered.  The  water  passed  through 
these  meters  was  30.4  percent  of  the  total  pumpage.  The  revenue  de- 
rived from  the  sale  of  metered  water  was  57.96  percent  of  the  total 
revenue  of  the  Water  Works. 

The  metered  water  consumers  paid  an  average  of  approximately 
six  and  one-fourth  cents  per  thousand  gallons  for  the  water  consumed. 
Approximately  seventy  percent  of  the  gross  pumpage  which  is  unme- 
tered  yielded  a  revenue  equivalent  to  approximately  two  cents  per  1,000 
gallons,  or  less  than  the  actual  cost  of  pumping. 

Water  waste  is  directly  reflected  in  the  costs  of  construction,  and 
the  cost  of  operating  the  Water  Works  plant.  In  the  past  thirty  years, 
during  which  the  population  and  the  mileage  of  mains  have  increased 
approximately  150  percent,  the  cost  of  im.provements  to  the  Water 
Works  and  the  average  daily  pumpage  have  increased  approximately 


102 


400  percent,  or  at  a  rate  two  and  a  half  times  as  fast  as  the  population. 

Pumpage  and  construction  costs  increase  at  approximately  parallel 
rates. 

Water  waste  results  in  deficient  water  pressures  throughout  the 
greater  part  of  the  city.  At  the  present  time  approximately  seventy-five 
percent  of  the  area  of  the  city  of  Chicago  suffers  from  inadequate  pres- 
sure during  periods  of  peak  consumption. 

Water  waste  decreases  the  effectiveness  of  fire  protection  service. 

Water  waste  is  directly  reflected  in  the  dry  weather  sewage  flow. 
It  therefore  increases  the  costs  of  constructing  intercepting  sewers,  sew- 
age pumping  stations  and  sewage  disposal  plants ;  it  is  also  directly  re- 
flected in  the  operating  costs  of  sewage  pumping  stations  and  sewage 
disposal  plants. 

Curtailment  of  Waste: 

Ample  precedent  and  experience  are  available  from  which  it  is 
practicable  to  determine,  within  reasonable  limits  of  accuracy,  the  possi- 
bilities of  waste  restriction  for  Chicago,  and  its  effect  upon  costs  of 
water  service  and  sewage  disposal.  Table  24  presents  the  data 
relative  to  results  accomplished  by  metering  in  eleven  American  cities. 
Figure  18  shows  diasframmatically  what  has  been  accomplished  by 
meters  in  these  and  other  cities.  Numerous  studies  have  been  made  of 
the  particular  problem  of  restricting  waste  of  water  in  this  city.   All  in- 

TABLE  24. 

EFFECT  OF  METERING  UPON  THE  CONSUMPTION  OF  WATER. 

Use  of  Water  in  Gallons  per  Service 


Before 

After 

Extensive 

Extensive 

City 

Metering 

Metering 

  1048 

396 

  1108 

734 

Cleveland,  0  

  1258 

688 

Milwaukee,  Wis  

  1314 

656 

Lowell,  Mass  

  630 

427 

  838 

396 

  853 

383 

  2240 

1165 

  1560 

508 

  1035 

635 

  755 

599 

  1149 

599 

  6.7 

95.0 

Average  reduction  by  increasing  meters  from  6.7%  to  95.0%  was 

from  1149  to  599  gallons  per  service  or  48%. 


103 


vestigators  have  been  in  substantial  accord  as  to  the  immense  savings 
in  cost  and  benefits  in  service  which  would  result  therefrom. 


Quite  recently,  at  the  mid-winter  convocation  of  the  Western 
Society  of  Engineers,  held  in  February,  1925,  Mr.  John  Ericson,  for 
nearly  thirty  years  city  engineer  of  Chicago,  presented  a  paper  on 
'THE  WATER  SUPPLY  PROBLEM  IN  RELATION  TO  THE 
FUTURE  CHICAGO."    In  this  paper  Mr.  Ericson  effectively  showed 


104 


the  need  of  metering  and  the  results  which  might  be  accompHshed  there- 

Mr.  Ericson  estimated  the  pumpage  requirements  which  the  Chica- 
go water  supply  would  be  called  upon  to  meet  if  the  present  system  of 
metering  were  to  continue,  and  also  what  these  requirements  would  be 
if  all  water  consumers  were  to  be  metered  within  the  next  ten-year 
period. - 

The  results  of  this  analysis  are  shown  in  diagrammatic  form  on 
Figure  19.  It  is  estimated  that  the  total  pumpage  in  1924,  of  approxi- 
mately 800,000,000  gallons  per  day  will  increase  to  2,200,000,000  gallons 
per  day  by  1960,  if  the  present  system  of  metering  is  continued.  If, 
however,  all  water  servtces  are  metered  within  the  next  ten  years  the 
total  pumpage  of  approximately  800,000,000  gallons  per  day  at  the  pres- 
ent can  be  reduced  to  approximately  520,000,000  gallons  per  day  in 
1935,  increasing  to  800,000,000  gallons  per  day  by  1960.  In  other 
words,  the  pumpage  with  universal  metering,  thirty-five  years  hence 
will  be  less  than  the  pumpage  at  the  present  time  with  but  ten  percent 
of  the  services  metered.  We  have  carefully  investigated  this  matter 
and  we  believe  that  Mr.  Ericson's  estimates  of  reduced  pumpage  are 
approximately  correct. 

This  fact  has  an  important  bearing  upon  water  works  construction 
costs.  No  additional  crib  intake  or  pumping  station  capacity  and  no 
expenditures  for  feeder  mains  would  be  required  for  the  next  thirty-five 
years  if  universal  metering  were  to  be  adopted. 

The  savings  to  the  Chicago  Water  Works,  due  to  metering,  have 
been  estimated  at  from  $225,000,000  to  $425,000,000  in  the  next  twenty- 
five  to  thirty-five  years.  Mr.  Ericson,  based  upon  a  population  of 
5,000,000  people  in  1960,  figures  that  the  saving  in  operation  up  to 
that  time  will  be  $117,000,000,  the  saving  in  repairs  and  renewals 
$43,000,000,  and  the  saving  in  additions  and  extensions  $143,000,000. 
Total  saving  $303,000,000.  This  saving  does  not  take  into  consideration 
fixed  charges  on  the  savings  in  new  construction,  which  if  taken  at  a 
rate  of  five  percent  and  based  upon  the  construction  expenditures  being 
made  at  a  uniform  rate  from  the  present  time  to  1960,  would  add  an 
additional  $125,000,000,  making  the  total  saving  to  the  Chicago  Water 
Works  amount  to  $428,000,000  by  1960. 

In  a  paper  "What  metering  would  do  for  the  Chicago  Water 
Works"  presented  before  the  Western  Society  of  Engineers  by  L.  R. 
Howson  on  February  1,  1923,  it  was  estimated  that  the  savings  prior  to 
1950,  due  to  universal  metering  would  be  $88,000,000  in  construction 
expenditures,  $145,000,000  in  operation,  including  saving  in  fixed 


105 


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I8oo 

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I20  0 

UJ 

looo 

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a 

6oO 

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or 

UJ 
Q. 
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2 

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UJ 


I&50    €>o     7o      8o  l^Joo    lo      2o     3o     4o      So  6o 

Year 


Figure  19. 


Effect  of  metering  the  Chicago  water  supply  upon  total  daily 
pumpage  and  per  capita  use. 


From  paper  by  John  Ericson  read  before  Western  Society  of  Engineers. 

charges,  total  saving  $233,000,000,  or  approximately  eight  and  one-half 
million  dollars  per  year. 

Other  estimates  have  been  made,  all  of  which  show  the  enormous 
savings  which  can  be  effected  by  metering.  The  exact  amount  is  not  of 
so  much  importance  when  the  lowest  estimates  that  have  been  made  by 
competent  engineers  investigating  this  matter  show  a  saving  in  the  next 
generation  of  over  $200,000,000. 

Effect  of  Metering  on  Intercepting  Sewers  and  Sewage  Disposal  Costs: 

The  amount  of  water  reaching  the  sewers  is  important  in  the  de- 
sign of  intercepters  and  sewage  disposal  works.  The  costs  of  a  large 
part  of  this  type  of  construction  are  directly  proportional  to  the  quan- 
tity of  sewage  to  be  treated. 


106 


Intercepting  Sezvers: 

The  capacity  of  intercepters  is  directly  affected  by  the  amount  of 
the  water  supply,  practically  all  of  which  reaches  the  sewers.  If  the 
water  pumpage  is  excessive  and  can  be  reduced  to  the  extent  of  thirty- 
five  percent  the  intercepting  sewer  sizes  can  be  reduced  about  twenty 
percent  and  the  cost  a  somewhat  smaller  percentage.  In  view  of  the 
large  mileage  of  intercepting  sewers  yet  to  be  built  the  question  of  the 
water  supply  and  its  eft'ect  upon  intercepter  sizes  is  important. 

At  the  present  time  the  intercepting  sewers  for  the  Des  Plaines  and 
Calumet  plants  have  been  completed.  The  intercepters  leading  to  the 
North  Side  plant  are  all  under  contract,  and  construction  is  well  on  to- 
ward completion.  The  intercepting  sewers  leading  to  the  West  and 
Southwest  plants  have  not  yet  been  started.  Intercepting  sewers  for 
the  West  Side  plant,  as  tentatively  designed  by  the  Sanitary  District, 
include  an  approximate  length  of  twenty  miles  of  large  size,  the  maxi- 
mum being  twenty-one  and  one-half  feet  in  diameter.  The  tentative 
design  of  the  intercepting  sewers  for  the  Southwest  plant  includes  some 
fifteen  miles  of  sewers,  varying  in  size  from  five  to  eighteen  feet.  In 
view  of  the  status  of  the  intercepting  sewers  for  these  two  plants  yet  to 
be  built,  it  is  pertinent  to  inquire  into  the  affect  of  metering  upon  the  de- 
sign and  costs  of  these  sewers. 

We  have  been  furnished  by  the  Sanitary  District  with  the  basis  of 
design  for  the  West  and  Southwest  sewers.  They  have  furnished  us 
with  the  drainage  areas  tributary  at  points  of  interception,  the  popula- 
tion estimated  as  being  located  on  each  drainage  area  in  1960,  the  in- 
dustrial use  as  estimated  by  the  Sanitary  District  in  cooperation  with 
the  City  Water  Department,  and  figures  as  to  infiltration.  The  total 
sewer  capacity  average  over  the  entire  district  amounts  to  600  gallons 
per  capita  per  day. 

Based  upon  figures  as  furnished  by  the  Sanitary  District,  the  tenta- 
tive design  made  by  the  District's  engineers  contemplates  that  the 
sewers  will  flow  three-fourths  full  under  peak  flow  conditions.  How- 
ever, under  the  use  of  water  estimated  by  Mr,  Ericson  and  others  under 
present  conditions  of  metering,  the  sewers  would  be  flowing  full  in- 
stead of  three- fourths  full  if  universal  metering  is  not  adopted.  The 
average  use  of  water  if  unmetered  will  be  440  gallons  per  capita  per  day. 
If  thirty-five  additional  is  added  for  the  peak  flow  excess  over  average 
the  entire  sewer  capacity  is  required. 

With  the  entire  water  supply  metered  the  average  use  of  water 
would  be  but  160  gallons  per  capita  per  day  or  280  gallons  per  capita 
per  day  less  than  if  the  present  system  is  continued.  Deducting  this 
amount  from  the  capacity  allowed  in  the  Sanitary  District's  estimates 


107 


an  equivalent  capacity  of  320  G.  P.  D.  per  capita  would  be  indicated. 
This  is  a  lower  figure  than  we  would  however  care  to  adopt  and  we 
have  arbitrarily  raised  it  to  375  gallons  per  capita  per  day.  The  effect 
of  metering  upon  sewer  costs  is  therefore  made  on  this  basis. 

The  sizes  of  sewers  required  under  both  the  metered  and  unmetered 
bases  have  been  determined  for  each  reach  of  the  intercepters  serving 
the  West  and  Southwest  areas  in  which  construction  for  sewage  dis- 
posal has  not  already  started.  Comparable  grades  and  velocities  were 
assumed. 

The  costs  of  the  intercepters  were  estimated  using  the  unit  prices 
developed  as  described  in  Part  X.  It  was  found  that  metering  will 
effect  a  saving  of  $3,105,500  in  the  cost  of  the  intercepters  to  the  West 
Side  plant,  and  $2,043,800  in  the  cost  of  the  intercepters  to  the  South- 
west Side  plant;  a  total  of  $5,149,300.  This  saving  results  from  meter- 
ing alone.  It  is  a  saving  perfectly  practicable  of  realization.  Metering 
must  eventually  come. 

Had  the  actual  costs  of  sewers  built  under  contracts  let  by  the 
Chicago  Sanitary  District  been  used  as  a  basis  of  the  comparison  the 
indicated  savings  would  have  been  much  greater. 

Metering  cannot  be  retroactive  in  saving  expenditures  on  sewers 
already  built ;  it  will  ,  however,  greatly  extend  the  period  of  adequacy 
of  such  sewers. 

In  view  of  the  ultimate  necessity  for  metering  the  Chicago  Water 
Supply,  as  agreed  by  all  engineers  who  have  given  it  thorough  study,  it 
would  seem  a  wise  procedure  to  give  due  consideration  to  this  question 
in  the  design  of  sewers  by  the  Sanitary  District.  Sewers  built  for  the 
present  without  meters  will  be  adequate  for  1960  with  meters. 

Effect  of  Metering  on  Sezvage  Disposal  Plant  Costs: 

The  cost  of  certain  parts  of  sewage  disposal  plants  varies  directly 
with  the  quantity  of  sewage  to  be  handled.  These  parts  include  pump- 
ing stations,  grit  chambers,  screens  and  aeration  tanks ;  other  parts  vary 
directly  with  the  solid  or  organic  load  of  the  sewage.  These  parts  in- 
clude sludge  chambers  of  Imhoff  tanks,  sludge  beds,  and  sludge  pressing 
and  drying  equipment,  for  activated  sludge  plants. 

Other  parts  of  the  plants  vary  in  a  ratio  which  is  neither  directly  in 
proportion  to  organic  load  nor  to  the  quantity  coming  to  the  plant.  This 
refers  particularly  to  air  compressor  equipment  and  to  sprinkling  filters. 
It  has  been  found  practicable  to  load  sprinkling  filters  handling  domestic 
sewage  with  2,000  to  4,000  people  per  acre  foot  depth  of  sprinkling 
filters.  It  has  also  been  found  practicable  to  put  sewage  through  these 
filters  at  rates  as  high  as  2,500,000  to  3,000,000  gallons  per  acre  per  day 
without  operating  difficulties. 


108 


The  following  table  shows  the  operating  rates  on  several  plants 
operating  satisfactorily  under  reasonably  heavy  loadings. 


Sprinkling 

Filter  Loads. 

City 

Pop. 

Acre  Fact  of 

Pop.  per  Sewage  per 

Served 

Stone  Filters 

Acre  foot  capita  (gal.) 

Lincoln,  Neb  

.  .  50,000  + 

D  X  ^.o  

-Id. 5 

0  AAA  1 
O,UU0  + 

OA 

80 

Madison,  Wis  

.  .  51,500 

6X2.5: 

=15 

(a)3400 

(a)102 

Columbus,  0  

.  .270,000(1920) 

51/3X10= 

:53.3 

5060 

100 

Atlanta,  Ga, 

Intrenchment   

,  30,000 

5%X2= 

:11.5 

2730 

167 

Lexington,  Ky  

.  28,000 

6X2: 

=12 

2330 

90 

Baltimore,  Md  

,  ,600,000(1924) 

8y2X30= 

=255 

(a)2360 

86 

As  operated  for  best 

results 

(a)3500 

Average   

3200 

104 

(a)    Excliisive  of  packing  house  waste. 


At  Baltimore  where  there  is  a  total  of  thirty  acres  of  stone  beds 
the  units  are  operated  so  as  to  maintain  as  nearly  as  possible  from  two 
and  one-half  to  three  million  gallons  per  acre  per  day  rate  (average  is 
from  2.79  to  2.91,  C.  E.  Keefer,  Engineering  News  Record,  2-7-24), 
the  equivalent  under  Balitmore  conditions  of  approximately  3500  people 
per  acre  foot  of  stone  beds. 

Included  in  this  optimum  loading  of  3500  people  per  acre  foot  of 
stone  filters  is  a  packing  house  waste,  which,  based  upon  weight  of  ani- 
mals slaughtered  per  capita  contributing  sewage  to  the  plant,  is  about 
thirty-five  percent  as  great  as  that  of  the  Chicago  stockyards  wastes. 

The  Madison  stone  filters,  aperating  satisfactorily  at  a  rate  of  3400 
people  per  acre  foot  have  in  addition  a  packing  house  waste  practically 
the  same  as  the  Chicago  stockyards  waste,  compared  on  a  slaughter 
weight  per  capita  basis. 

A  study  of  the  effectiveness  of  sprinkling  filters  in  reducing  the 
biochemical  oxygen  demand  shows  that  the  Baltimore  and  Columbus 
filters  reduce  the  demand  sixty-seven  and  fifty-five  percent  respectively 
as  compared  to  thirty-one,  thirty-one  and  forty-nine  percent  respectively 
for  the  two  Atlanta  and  Fitchburg  plants  with  population  loads  per 
acre  foot,  but  about  half  of  those  at  Baltimore  and  Columbus. 

It  is  our  opinion  that  good  operation  may  be  secured  within  the 
upper  limits  of  at  least  3,000  people  per  acre  foot,  and  three  million 
gallons  per  acre  per  day  for  six  foot  stone  beds. 

As  with  a  per  capita  use  of  160  gallons  per  day  the  population 
served  by  a  six  and  one-half  foot  filter  operating  at  a  three  M.  G.  D. 
per  acre  rate  would  be  about  2850  per  acre  foot  the  rate  of  liquid  dosage 


109 


rather  than  the  population  load  is  considered  the  limiting  factor  in  com- 
paring the  cost  of  sprinkling  filters  at  Chicago  under  metered  and  un- 
metered  conditions. 

In  the  estimated  savings  on  the  item  of  sprinkling  filters,  ef¥ected 
by  metering,  we  have  therefore  assumed  that  the  more  dilute  sewage, 
tinder  unmetered  conditions,  would  have  a  direct  effect  on  area  and  cost 
of  beds.  In  other  words,  if  the  quantity  of  sewage  is  doubled  due  to 
water  waste  the  area  and  cost  of  stone  beds  would  likewise  be  doubled 
compared  to  areas  and  costs  under  fully  metered  conditions. 

The  effect  of  metering  upon  plants  already  built  is  to  prolong  their 
period  of  usefulness  and  defer  the  time  at  which  additions  will  be  re- 
quired. Each  plant  has  been  analyzed  in  its  component  parts,  its  capa- 
cities studied  with  reference  to  future  needs  under  metered  and  unmet- 
ered water  supply  conditions,  and  the  savings  effected  by  universal 
metering  ascertained. 

The  following  is  a  summarization  of  the  savings  which  universal 
metering  will  effect  in  the  future  construction  costs  of  intercepters  and 
sewage  disposal  works. 

Savings  in  intercepter  costs  are  computed  for  1960  quantities ;  dis- 
posal plants  for  1945  conditions. 

The  total  savings  of  approximately  $50,000,000  do  not  include  any 
savings  in  the  construction  cost  of  sewage  disposal  works  to  the  Chicago 
Sanitary  District  after  1945.  The  savings  cover  the  cost  of  construction 
only,  operating  cost  not  having  been  taken  into  consideration  in  this 
part  of  the  study. 

The  small  estimated  saving  with  a  flow  of  4167  c.  f.  s.  results  from 
the  fact  that  a  larger  part  of  the  cost  of  an  activated  sludge  plant  is  in- 
dependent of  liquid  volume  than  is  the  case  with  a  sprinkling  filter  plant. 
The  sludge  drying  and  pressing  equipment  varies  only  with  the  solid 
content  which  is  in  turn  independent  of  the  dilution  of  the  sewage. 

The  4167  c.  f.  s.  project  is  the  only  one  contemplating  activated 
sludge  treatment  at  the  West  and  Southwest  Side  plants. 

Savings  in  Operating  Costs: 

The  restriction  of  water  waste  will  also  have  a  marked  effect  upon 
operating  costs  of  pumping  stations  and  disposal  works.  Practically  all 
the  costs  of  sewage  treatment  in  plants  such  as  herein  considered  vary 
nearly  in  proportion  to  Hquid  quantities,  except  costs  incident  to  sludge 
handling  and  sludge  drying,  which  are  practically  independent  of  liquid 
volume.  In  estimating  the  savings  in  operating  cost  due  to  metering, 
the  following  bases  have  been  assumed : 

(a)    The  cost  of  power  varies  directly  with  the  liquid  volume. 

(h)    Pumping  station  labor  costs  vary  at  a  rate  of  fifty  percent  as 


110 


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great  as  the  variation  in  liquid  volume,  i.  e.  if  the  liquid  volume  is 
doubled  the  station  labor  is  increased  fifty  percent. 

(c)  Labor  for  sewage  treatment  plant  operation  varies  as  above 
for  station  labor  as  the  costs  are  approximately  fifty  percent  determined 
by  liquid  volume  and  fifty  percent  by  total  solids  or  sludge. 

The  estimated  savings  in  disposal  plant  operating  expenses  result- 
ing from  metering  of  the  water  supply  have  been  estimated  as  above 
outlined  for  the  year  1945.  The  savings  vary  from  $3,000,000  to 
$4,000,000  per  year  depending  upon  the  treatment  processes  necessary 
with  the  flows  in  the  channel  varying  from  10,000  c.  f.  s.  to  4167  c.  f.  s. 

TABLE  26. 

SAVINGS  IN  OPERATING  COSTS  (1945) 
OF  SEWAGE  DISPOSAL  WORKS  (EXCLUSIVE  OF  FIXED  CHARGES)  — 
EFFECTED  BY  METERING  THE  WATER  SUPPLY. 

Cubic  Feet  per  Second  Flow  in  Channel. 
Plant  4167  6000  7500  8500  10000 

Calumet   $  174,750    $  174,750    $   174,750    $  174,750    $  174,750 

North  Side    947,000        947,000        947,000        947,000  947,000 

West  Side   1,869,500     1,288,500     1,288,500        968,000  968,000 

Southwest  Side   1,289,500        850,800        636,800        850,800  850,800 

Total  Annual   $4,230,750    $3,261,050    $3,047,050    $2,940,550  $2,940,550 

Basis. 

Sta.  labor  varies  50%  with  liquid  volume — 50%  not  affected  by  volume. 
Power  varies  directly  with  liquid  volume. 

Treatment  plant  operating  cost  varies  50%  with  liquid  volume  and  50% 
with  solids. 

These  savings  in  operating  cost  do  not  include  savings  in  fixed 
charges  which  at  four  percent  for  interest  and  two  percent  for  deprecia- 
tion reserve  would  amount  to  from  $2,500,000  to  $3,000,000  per  year 
in  1945. 

The  estimated  saving  in  operating  cost  resulting  from  metering 
for  each  flow  is  shown  in  the  table  included  herewith. 

Summarisation  of  Savings  by  Metering: 

A  study  of  the  estimated  savings  to  the  Chicago  Water  Department 
during  the  thirty-five  year  period  to  1960  and  other  estimated  savings 
for  other  periods  would  lead  us  to  believe  that  not  less  than  $200,000,000 
to  $225,000,000  would  represent  a  fair  measure  of  the  total  savings 
(including  interest)  to  the  Chicago  Water  Works  prior  to  1945  if 
meters  were  adopted  and  universally  installed  within  ten  years.  Add 


112 


to  this  $200,000,000  saving  in  the  water  works,  an  additional  saving  of 
$40,000,000  to  $53,000,000  in  sewers  and  sewage  disposal  and  the 
amount  becomes  $240,000,000  to  $253,000,000  saved  in  twenty  years, 
an  average  of  over  $12,500,000  per  year,  through  the  introduction  of 
universal  metering,  and  without  crediting  any  savings  after  1945. 

An  additional  amount  reaching  $3,000,000  to  $4,000,000  per  year 
in  1945  will  be  saved  in  operating  costs  of  pumping  stations  and  treat- 
ment works. 

Magnitude  of  Savings: 

The  estimated  saving  of  approximately  $250,000,000  in  twenty 
years  is  so  great  that  it  will  in  addition  to  installing  meters  at  a  cost 
of  approximately  $10,000,000  build  complete  filtration  works  for  the 
Chicago  water  supply  at  an  estimated  cost  of  $26,000,000  (Mr.  Ericson's 
W.  S.  E.  paper)  finance  complete  sewage  disposal  for  the  entire  city 
and  still  leave  over  $100,000,000  net,  which  would  be  more  than  enough 
to  acquire  the  elevated  lines  and  make  a  good  start  toward  the  subway 
system. 

Effect  of  Metering  on  Water  Sermce: 

In  addition  to  the  financial  advantages,  metering  alone  will  double 
the  average  pressure  in  the  water  m.ains  of  the  city,  and  will  enable  the 
water  works  to  furnish  all  consumers  adequate  service,  where  but 
twenty-five  percent  now  have  it. 

Water  metering  will  make  filtration  possible.  Without  it  Chicago 
must  continue  to  drink  unfiltered  and  at  times  turbid  lake  water,  highly 
chlorinated  with  resulting  tastes  and  odors. 

Eifect  of  Metering  Upon  Protection  of  Health: 

Few  sanitary  engineers  will  dispute  the  assertion  that  $36,000,000 
spent  for  meters  and  filtration  plants  will  do  more  to  protect  the  people 
of  Chicago  from  water-borne  disease  than  will  an  equal  or  larger 
amount  spent  for  sewage  disposal  works. 

It  has  been  estimated  that  with  a  diversion  of  but  4167  c.  f.  s.  there 
would  be  from  seven  to  eight  reversals  of  flow  with  discharge  of  sewage 
into  the  lake  each  year  (see  memorandum  concerning  drainage  and 
sewage  conditions  at  Chicago,  Sanitary  District,  December,  1923).  It  is 
believed  to  be  a  safe  assertion  that  seven  or  eight  reversals  with  filtra- 
tion would  be  much  less  hazardous  than  the  one  to  four  reversals  now 
occurring. 

Filtration  is  the  first  line  of  defense  against  water  borne  disease. 
Its  results  are  positive,  continuous  and  effectual.  It  has  repeatedly 
demonstrated  its  ability  to  safeguard  the  public  health. 


113 


Filtration  is  only  practicable  at  Chicago  if  universal  metering  is 
adopted.  Its  cost,  together  with  large  additional  savings,  can  be  re- 
covered by  metering.   Metering  is,  therefore  urgent  to  : 

(a)  Protect  health  against  water  borne  disease. 

(b)  Enable  the  water  plant  to  furnish  adequate  service  and  pres- 
sure 

(c)  Prevent  wasteful  expenditures  for  the  waterworks. 

(d)  Prevent  wasteful  expenditures  for  intercepting  sewers  and 
se\vage  disposal  works. 


114 


PART  IX. 

VOLUME  OF  SEWAGE. 

The  volume  of  sewage  liquid  to  be  treated  is  dependent  upon : 
1st.    Tributary  population. 
2nd.    The  total  water  use,  and 
3rd.  Infiltration. 

So  far  as  the  sewage  contributed  by  the  domestic  population  of  the 
Chicago  Sanitary  District  is  concerned,  practically  the  entire  amount 
will  be  collected  in  the  five  major  sewage  disposal  plants;  viz.  The 
Des  Plaines,  Calumet,  North  Side,  West  Side  and  Southwest  side.  The 
distribution  of  the  population  for  the  present  and  for  each  five  year 
period  up  to  1945,  is  shown  on  Table  27. 

It  will  be  noted  that  the  total  population  tributary  to  these  five 
major  plants  is  somewhat  less  than  the  total  population  of  the  district 
as  estimated  in  Part  III,  and  as  shown  in  this  table.  It  is  estimated  that 
approximately  105,000  people  residing  in  the  district  are  not  tributary 
to  any  one  of  these  five  plants  at  the  present  time,  and  that  it  is  probable, 
due  to  the  rapid  expansion  of  the  suburban  area,  that  this  number  will 
gradually  increase  and  reach  approximately  300,000  people  by  1945. 
The  sewage  originating  from  this  population  must  either  be  treated  by 
outlying  plants  or  by  pumping  to  one  of  the  major  plants. 


TABLE  27. 

POPULATION  TRIBUTARY  TO  EACH  OF  THE  FIVE  MAJOR  SEWAGE 

DISPOSAL  PLANTS. 


Popula- 
tion, by 
Sanitary 
District 


Disposal 

Plant  1925 
Des  Plaines  . .  50,000 

Calumet    190,000 

N.  Side    690,000 


I  W.  Side*  . 
I  S.  W.  Side. 


.1,370,000 
.•  950,000 


1930 
60,000 
225,000 
800,000 
1,430,000 
1,040,000 


1935 
75,000 
255,000 
915,000 
1,490,000 
1,135,000 


1940 
90,000 

290,000 
1,015,000 
1,550,000 
1,230,000 


1945 
105,000 
320,000 
1,125,000 
1,615,000 
1,322,000 


Total  5  Major  Plants  3,250,000    3,555,000    3,870,000    4,175,000  4,487,000 

Misc.  Plants    105,000      155,000      200,000      250,000  298,000 


Total  Population  of  Dist.  .3,355,000    3,710,000    4,070,000    4,425,000  4,785,000 


*Excl.  of  300,000  transient  loop  population. 


115 


The  table  showing  the  distribution  of  the  total  population  of  the 
district  over  the  five  plants  leaves  out  of  consideration  the  floating  or 
transient  population,  largely  centered  over  the  area  tributary  to  the 
West  Side  plant,  which  embraces  the  loop  district.  This  floating  popu- 
lation is  estimated  at  300,000  people,  both  for  the  present  and  for  1945, 
and  in  the  quantities  of  sewage  which  are  estimated  as  reaching  the 
West  side  plant,  the  resident  population  has  arbitrarily  been  increased 
300,000  people  to  care  for  the  transient  population. 

This  figure  of  300,000  is  considered  as  representative  of  the  purely 
transient  population  plus  that  part  of  the  working  or  day  population 
which  is  employed  in  Chicago,  largely  in  the  area  to  be  served  by  the 
West  side  plant,  and  which  lives  outside  of  the  area  served  by  the  Sani- 
tary District.  It  necessarily  is  a  more  or  less  approximate  figure,  but 
is  probably  as  accurate  as  can  be  reasonably  determined.  Some  allow- 
ance obviously  must  be  made  in  a  city  such  as  Chicago  to  care  for  this 
sewage  load  contributed  to  the  total  by  those  not  enumerated  in  the 
Chicago  census  figures. 

The  quantity  of  sewage  to  be  treated  at  each  of  the  five  major 
plants  has  been  estimated  from  a  study  of  the  population  tributary  to 
each,  and  has  been  estimated  upon  two  bases,  viz.  (a)  under  the 
present  system  of  metering,  and  (b)  universal  metering  of  the  water 
supply. 

The  greater  part  of  the  population  residing  within  the  Chicago 
Sanitary  District  receives  its  water  supply  from  the  City  of  Chicago. 
The  total  pumpage  of  the  Chicago  Water  Works  for  the  year  1923, 
averaged  807,000,000  gallons  daily,  which  the  Chicago  Water  Depart- 
ment estimates  as  having  been  supplied  to  3,062,532  people,  of  which 
approximately  150,000  were  outside  of  the  city  of  Chicago  but  within 
the  Chicago  Sanitary  District  limits. 

In  addition  to  the  pumpage  by  the  Chicago  Water  Department, 
some  water  reaches  the  sewers  from  private  water  supplies  developed 
by  industries  and  from  the  supplies  of  suburban  cities  within  the  area 
of  the  Sanitary  District  of  Chicago.  There  are  a  few  industries  develop- 
ing considerable  supplies,  notably  those  in  the  Stockyards  and  Corn 
Products  districts. 

There  is  also  a  small  population  supplied  from  municipal  supplies 
within  the  Sanitary  District  other  than  the  City  of  Chicago,  the  largest 
of  which  is  the  Evanston  supply.  Others  are  those  at  LaGrange,  River 
Forest,  Forest  Park,  Summit,  etc.  While  we  have  no  data  as  to  the 
total  amount  of  water  pumped  by  industries  and  municipalities  other 
than  Chicago,  within  the  Chicago  Sanitary  District,  it  is  believed  that  in 
total  amount  it  does  not  exceed  five  percent  of  the  water  pumped  by 


116 


the  City  of  Chicago.  Most  of  the  water  pumped,  in  addition  to  that 
pumped  by  the  City  of  Chicago,  is  furnished  under  metered  conditions, 
with  waste  well  restricted. 

The  total  population  of  the  cities  and  villages  in  the  Sanitary  Dis- 
trict (excluding  Chicago)  has  increased  from  89,703  in  1900  to  276,930 
in  1920.  Based  upon  an  average  use  of  100  gallons  per  day,  the  total 
water  used  by  these  villages  would  be  about  30,000,000  gallons  per  day 
at  the  present  time,  or  about  four  percent  of  the  average  daily  pumpage 
of  Chicago.  The  industries  probably  use  enough  well  water  to  raise 
the  total  to  approximately  five  percent  of  the  Chicago  pumpage.  Table 
5  shows  the  population  of  each  of  the  cities  and  villages  in  the 
Sanitary  District. 

Infiltration  of  ground  water  into  the  sewers  is  quite  indeterminate 
in  amount.  The  Sanitary  District  of  Chicago  has  substantially  no 
figures  which  would  furnish  reliable  information  to  be  used  as  a  basis 
for  the  amount  of  infiltration  into  the  sewers  of  the  various  sections  of 
the  city  under  varying  soil  conditions.  No  measurements  are  recorded 
by  the  city.    Such  data  as  are  available  are  fragmentary  only. 

The  city  of  Chicago  has  designed  its  pumping  stations  on  the  basis 
of  100  gallons  per  acre  per  day  infiltration  in  clay  soils  and  1000  gallons 
per  acre  per  day  in  sandy  soils.  City  sewer  sizes  are  determined  by 
flood  flows.  The  greater  part  of  the  city  of  Chicago  has  a  dense  clay 
soil,  through  which  infiltration  into  the  sewers  is  low.  A  comparatively 
small  area  is  sandy.  The  Sanitary  District  of  Chicago  has  made  its 
preliminary  design  of  the  West  Side  intercepters,  using  an  infiltration 
allowance  of  approximately  2000  gallons  per  acre  per  day.  The  average 
flow,  which  is  the  governing  consideration  in  sewage  disposal  plant  de- 
sign, is  very  much  less  than  this  amount.  It  is  believed  that,  taken  as  an 
average  over  the  entire  Sanitary  District  area,  the  infiltration  of  ground 
water  into  the  sewers  is  very  small  in  amount.  In  th€  computations 
hereinafter  made  in  Part  IX,  the  infiltration  has  been  based  upon  750 
G.  Po  D.  per  acre  which  results  in  the  infiltration  about  one-sixth  of  the 
domestic  flow  or  six  percent  of  the  total  flow  estimated  for  the  West 
Side  intercepter. 

A  part  of  the  water  supply  never  reaches  the  sewers.  It  is  used 
for  sprinkling  and  other  uses  which  do  not  contribute  to  the  sew- 
age flow.    The  amount  of  water  lost  in  this  way  is  alos  indeterminate. 

Taken  as  a  general  average  under  the  conditions  prevailing  here  in 
Chicago,  it  is  probable  that  if  the  infiltration  of  ground  water  into  the 
sewers  is  considered  equal  to  that  part  of  the  supply  which  does  not 
reach  the  sewers,  the  result  will  be  not  far  from  correct.   This  has  been 


117 


the  basis  upon  which  the  size  of  the  sewage  disposal  plants  outlined  in 
this  report  has  been  predicted. 

We  have  prepared  a  table  based  upon  the  estimated  population  and 
the  water  use  under  universally  metered  and  unmetered  conditions, 
showing  the  amount  of  sewage  which  it  will  be  necessary  to  treat  at 
each  of  the  five  major  plants  for  each  five  year  interval  from  the  present 
to  1945. 

The  last  line  of  this  table  shows  the  sewage  flow  per  capita  for  the 
entire  Sanitary  District.  It  will  be  noted  that,  under  metering,  the 
total  amount  of  sewage  averages  from  170  to  171  gallons  per  capita 
per  day  as  compared  to  the  water  consumption  previously  estimated 
herein  at  160  gallons  per  capita  per  day  under  completely  metered  con- 
ditions. The  discrepancy  is  due  to  the  fact  that  in  estimating  the  quan- 
tity of  sewage  reaching  the  West  Side  plant,  there  has  arbitrarily  been 
added  the  flow  originating  from  the  300,000  floating  population  in  that 
area. 

So  far  as  the  West  Side  plant  alone  is  concerned,  the  basis  is  be- 
lieved to  be  the  correct  procedure.  It  is  also  correct  insofar  as  this 
floating  population  represents  the  population  originating  outside  the 
boundaries  of  the  Sanitary  District  of  Chicago.  Insofar  as  it  includes 
the  population  originating  within  the  Sanitary  District  of  Chicago,  and 
simply  transferred  during  the  working  hours  from  the  area  tributary 
to  one  of  the  other  major  sewage  disposal  plants  to  the  West  Side  plant 
area,  it  results  in  an  over-estimate  of  the  quantities  taking  the  city  as  a 
whole. 

TABLE  28. 

QUANTITIES  OF  SEWAGE  TO  BE  TREATED  UNDER  UNIVERSAL 
METERING  AND  PRESENT  METERING  OF  WATER  SUPPLY. 

Plant  1925        1930  1935  1940  1945 

Million  Gallons  Sewage  Daily 


(a) 

(b) 

(a) 

(b) 

(a) 

(b) 

(a) 

(b) 

(a) 

Des  Plaines  . . 

5 

6 

6 

8 

8 

9 

9 

10 

10 

Calumet   

53 

50 

67 

41 

83 

46 

102 

51 

118 

North  Side  . . . 

193 

176 

240 

145 

297 

163 

354 

180 

416 

West  Side  

370 

316 

429 

286 

485 

296 

542 

306 

595 

4-  114 

S.  W.  Side.... 

256 

229 

312 

182 

370 

197 

430 

222 

490 

Totals   

877 

777 

1054 

662 

1243 

711 

1437 

769 

1629 

(1743) 

Ave.  G.P.D.  per 

cap  

262 

219 

296 

171 

322 

170 

344 

171 

364 

(390) 

(a)  Present  system  of  metering. 

(b)  Universal  metering. 


118 


This  allowance  is,  however,  in  the  nature  of  a  factor  of  safety  in- 
sofar as  it  is  affected  by  the  shifting  of  populations  from  one  plant  to 
the  other.  If  half  the  loop  is  assumed  as  originating  within  the  Sanitary 
District  boundaries,  this  allowance  for  the  West  Side  plant  is  equivalent 
to  including  an  allowance  of  approximately  150  gallons  per  acre  per  day 
for  infiltration. 

Table  28  is  a  summarization  of  the  quantities  of  sewage  flow 
to  be  expected  at  each  of  the  five  major  plants  under  universal  metering 
and  under  present  conditions  of  metering  of  the  water  supply  from  1925 
to  1945. 


119 


PART  X. 

FUTURE  INTERCEPTING  SEWER  CONSTRUCTION. 

At  the  present  time  there  are  approximately  150  sewer  outlets 
emptying  into  the  Chicago  River  and  the  Drainage  Canal.  The  outlets 
on  the  North  Branch  as  far  south  as  Fullerton  Avenue  are  all  to  be  in- 
tercepted by  the  North  side  intercepting  sewers  for  which  contracts  have 
already  been  let.  These  intercepters  serve  the  North  Side  treatment 
works.  The  present  outlets  from  Fullerton  Ave.  South  and  West 
along  the  river  and  main  Drainage  Canal  as  far  as  the  village  of  Sum- 
mit, are  yet  to  be  intercepted  and  the  dry  weather  flow  carried  to  the 
proposed  West  and  Southwest  Side  disposal  plants  to  be  located  in  the 
vicinity  of  Summit. 

All  but  about  thirty-five  miles  of  the  total  length  of  intercepters 
required  have  already  been  built.  Of  this  thirty-five  miles,  twenty  miles 
will  be  required  to  collect  the  sewage  and  carry  it  to  the  West  Side  plant 
and  fifteen  miles  will  be  required  for  the  Southwest  Side  plant. 

Basis  of  Intercepter  Design: 

A  glance  at  the  map,  Figure  3,  shows  the  routes  of  the  pro- 
posed West  and  Southwest  Side  intercepting  sewers.  In  general  they 
parallel  the  river  and  the  Drainage  Canal,  extending  along  both  sides 
of  these  channels  from  Fullerton  Ave.  on  the  North  Side,  southerly  to 
the  main  channel  where  they  are  joined  by  intercepters  laid  from  the 
lake  westerly,  thence  through  the  highly  congested  central  district  and 
along  the  Drainage  Canal  to  the  vicinity  of  Summit. 

In  most  of  this  length  the  congestion  is  such  as  to  almost  preclude 
open  cut  methods  of  construction.  The  Sanitary  District  has  accordingly 
adopted  tunnel  methods  of  construction,  for  which  the  heavy  clay  soil 
of  this  district  is  admirably  adapted.  The  tunnels  are  in  general  at 
shallow  depths  below  the  street  surface. 

Other  cities  such  as  Milwaukee,  Detroit  and  Cleveland  are  using 
tunnel  rather  than  open  cut  methods  quite  largely.  On  paved  streets  in 
Milwaukee  it  has  been  found  economical  to  use  tunnels  in  constructing 
pipe  sewers  as  small  as  ten  inches  or  twelve  inches  in  diameter. 

With  the  conditions  prevailing  in  Chicago,  the  adoption  of  tunnel- 
ing rather  than  open  cut  methods  will  probably  be  economical,  and  will 
greatly  reduce  inconvenience  to  the  public. 


120 


The  Chicago  Sanitary  District  has  tentative  designs  for  the  West 
and  Southwest  Side  intercepting  sewers,  the  results  of  which  have  been 
furnished  to  us  for  our  study. 

An  analysis  of  the  design  of  the  West  Side  intercepters  serving 
about  1,350,000  resident  and  300,000  loop  or  transient  population  has 
been  made.  In  general  the  analysis  shows  that  approximately  143 
gallons  per  capita  per  day  has  been  allowed  for  domestic  water  supply 
(including  the  transient  use  as  domestic)  an  average  of  approximately 
2,050  gallons  per  acre  per  day  (equivalent  to  34  gallons  per  capita  per 
day  1960  population)  has  been  allowed  for  infiltration  and  an  additional 
allowance  for  industrial  water  uses,  amounting  to  approximately  the 
equivalent  of  120  gallons  per  capita  per  day.  All  of  these  units  are 
based  upon  the  sum  of  fixed  and  transient  populations.  The  total  water 
reaching  the  sewers  under  average  conditions  is,  therefore,  300  gallons 
per  capita  per  day  under  this  design.  This  amount  is  increased  by  ap- 
proximately fifty  percent  giving  a  peak  rate  flow  of  450  gallons  per 
capita  per  day,  which  is  then  further  increased  by  one-third  in  order  to 
provide  for  one- fourth  of  the  sewer  capacity  always  being  available  for 
ventilation.  The  sewers  as  tentatively  designed  by  the  Sanitary  Dis- 
trict are,  therefore,  laid  out  on  a  basis  equivalent  to  600  gallons  per 
capita  for  the  1960  population. 

It  is  believed  that  this  total  allowance,  while  it  includes  a  larger 
allowance  for  ground  water  than  we  would  consider  necessary  for  Chi- 
cago conditions,  is  in  the  aggregate  approximately  correct  as  represen- 
tative of  the  conditions  of  flow  in  the  intercepting  sewers  if  the  Chicago 
water  supply  is  to  remain  unmetered.  It  has  previously  been  shown  that 
if  meters  are  not  installed  the  per  capita  use  in  1960  will  approximate 
440  gallons  per  capita  per  day.  If  this  is  increased  by  thirty-five  per- 
cent to  care  for  peak  flows  (i.  e.  150  gallons  per  capita  per  day  which 
is  fifty  percent  of  the  300  gallons  per  capita  per  day  used  by  the  Dis- 
trict). The  total  of  600  G.  P.  D.  per  capita  used  by  the  Sanitary  Dis- 
trict would  result.  The  Sanitary  District  design,  therefore,  would  not 
allow  any  excess  capacity  for  ventilation  in  1960,  if  meters  are  not 
adopted. 

It  is,  however,  inconceivable  that  the  Chicago  water  supply  will 
remain  unmetered  another  thirty-five  years.  It  is  not  believed  to  be 
good  economic  engineering  to  design  long  lived  structures,  such  as 
intercepters  for  populations  expected  thirty-five  years  in  the-  future 
and  under  the  worst  possible  conditions  of  water  waste.  The  necessity 
for  metering  is  so  urgent  and  the  benefits  from  it  so  great  that  it  is  in 
our  opinion  decidely  unwarranted  to  base  intercepting  sewer  designs 
upon  a  continuation  of  impossible  water  uses.    Universal  metering  will 


121 


effect  a  reduction  in  use  per  capita  for  the  anticipated  1960  conditions  of 
approximately  280  gallons  per  capita  per  day  which  amount  in  our 
opinion  may  be  safely  deducted  in  computing  the  required  capacity  of 
the  intercepting  sewer  system.  In  other  words,  an  intercepting  sewer 
designed  on  the  basis  of  320  gallons  per  capita  per  day  with  universal 
metering  will  be  fully  as  adequate  as  the  sewers  designed  without  meter- 
ing on  a  basis  of  600  gallons  per  capita  per  day,  the  figure  used  by  the 
Chicago  Sanitary  District. 

Basis  of  Design: 

In  Computing  the  capacity  required  for  the  West  Side  intercepters 
we  have  adopted  the  following  bases : 

(a)  Population  tributary  1,370,389  (furnished  from  Sanitary  Dis- 
trict figures),  floating  or  transient  population  in  loop  300,000  people. 

(b)  Domestic  water  use  75  gallons  per  capita  per  day  of  resident 
and  floating  population. 

(c)  Infiltration  at  the  average  rate  of  750  gallons  per  acre  per 

day. 

(d)  Industrial  use,  as  estimated  by  the  Chicago  Sanitary  District, 
with  the  exception  of  the  loop  population,  the  sewage  of  which  we  have 
considered  as  domestic. 

The  total  average  sewage  flow  from  this  district  for  1960  is  thus 
estimated  as : 

(a)  Domestic  flow  125  MGD.  equivalent  to    75      GPD.  per  capita 

(b)  Infiltration       21  MGD.  equivalent  to    12>^  GPD.  per  capita 

(c)  Industrial  uses  204  MGD.  equivalent  to  122     GPD.  per  capita 


Total  350  MGD.  equivalent  to  2091/2  GPD.  per  capita 

Adding  to  this  average  flow  approximately  forty-five  percent  (90 
G.P.D.  per  cap) for  the  excess  peak  rate  and  allowing  sewer  capacity 
sufficient  to  provide  one-third  additional  for  ventilation,  a  total  design 
capacity  of  375  gallons  per  capita  per  day  is  secured. 

With  the  above  as  a  basis,  the  intercepting  sewers  for  the  West 
and  Southwest  treatment  plants  have  been  tentatively  laid  out. 

The  West  Side  intercepter  includes  approximately  twenty-one  miles 
of  sewers,  varying  in  size  from  seven  feet  to  seventeen  feet.  The 
Southwest  Side  intercepter  has  a  total  length  of  approximately  fifteen 
miles,  varying  in  size  from  four  feet  to  fourteen  feet  three  inches  in 
diameter. 

The  routes  of  the  intercepters  are  as  tentatively  laid  out  by  the 
Sanitary  District  and  are  substantially  as  shown  on  Figure  3.    The  in- 


122 


vert  elevations  at  the  disposal  plants  will  be  approximately  thirty  feet 
below  lake  level. 

Intercepting  Sewer  Costs: 

In  view  of  the  large  expenditures  involved  in  the  construction  of 
intercepting  sewers  yet  to  be  built  we  have  thought  it  advisable  to  ascer- 
tain the  facts  relative  to  the  costs  of  building  intercepting  sewers  in 
other  large  cities  of  the  country.  We  have  accordingly  made  investiga- 
tions of  the  cost  of  sewer  construction  in  Milwaukee,  Detroit,  Phila- 
delphi,  Cleveland  and  St.  Louis.  All  of  these  places  have  been  visited 
and  the  facts  relative  to  costs,  labor  conditions,  difficulties  encountered 
in  construction  and  other  facts  having  a  bearing  upon  and  being  neces- 
sary to  an  adequate  interpretation  of  costs  were  secured. 

It  was  found  that  a  large  mileage  of  sewers  up  to  fourteen  feet  in 
diameter  have  been  constructed  within  recent  years  under  contracts 
relative  to  which  it  was  possible  to  secure  complete  information.  An 
analysis  of  all  of  the  recent  contract  lettings  in  all  of  these  cities  was 
made,  and  the  data  thus  secured  is  shown  in  Figure  20. 

Inasmuch  as  the  construction  of  these  sewers  extended  over  the 
past  period  of  approximately  five  years  in  most  cases,  during  which  time 
there  have  been  rather  violent  fluctuations  in  labor  and  material  costs, 
the  costs  in  each  particular  instance  have  been  reduced  to  present  day 
equivalent  costs  in  the  cities  in  which  these  contracts  were  executed. 

Further  correction  was  then  made  in  order  to  give  adequate  consid- 
eration to  the  relation  of  costs  in  these  other  cities  to  costs  in  Chicago. 
These  adjustments  were  made  on  the  basis  of  the  labor  scales  prevailing 
in  other  cities  and  in  Chicago,  and  upon  the  proportions  of  labor  and 
materials  entering  into  the  several  types  of  construction  and  sizes  of 
sewers.   These  adjusted  costs  are  shown  in  Figure  21. 

Variation  in  Conditions: 

The  soil  conditions  in  the  various  cities  and  under  the  large  num- 
ber of  contracts  analyzed  varied  quite  materially.  We  endeavored  to 
ascertain  the  facts  in  all  cases  in  order  that  we  might  interpret  the  cost 
data  secured. 

Of  the  several  sewer  contracts  executed  on  the  Cleveland  inter- 
cepting sewers,  only  three  were  constructed  under  conditions  similar  to 
those  prevailing  in  Chicago  through  the  district  yet  to  be  served  with 
intercepters.  Four  of  the  sewers  were  constructed  in  whole  or  in  part 
in  quicksand  or  in  wet  soil  conditions  which  made  the  use  of  air  neces- 
sary. In  our  application  to  Chicago  conditions  these  sewers  were  elim- 
inated. 


123 


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Figure  20. — Construction  costs  of  sewers  in  tunnel,  at  actual  prices  paid. 


124 


Diagram  showing 

Construction  Costs  or  "DEVAjELR-b 
iisTuhhELL- Adjusted  to 
Chicago  1925  Basis 


275 


To  Accompanij    Rcpor+  o-P 

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Figure  21. — Construction  costs  of  sewers  in  tunnel,  adjusted  to  Chicago 

1925  basis. 


125 


At  Detroit  it  was  found  that  the  conditions  of  excavation  more 
closely  resembled  those  in  Chicago  than  in  any  of  the. other  cities  visited. 
The  Detroit  conditions  are,  therefore,  peculiarly  comparable,  so  far  as 
costs  are  concerned.  Detroit  has  also  been  very  active  in  sewer  con- 
struction work.  Over  fifty  contracts  covering  sewers  from  twelve  inches 
to  fourteen  feet  in  diameter  have  been  executed  in  the  past  three  years. 
Tunnel  work  has  been  done  on  sizes  twenty-four  inches  and  larger. 

Analysis  of  Detroit's  bids  shows  good  competition  to  have  been 
■secured  in  which  many  of  the  best  sewer  contractors  of  the  country 
participated.  The  range  of  prices  bid  indicates  that  the  work  is  being 
done  under  conditions  which  secure  good  work  at  reasonable  costs. 

The  Detroit  contracts  are  platted  on  Figure  20  which  indicates  the 
uniformity  of  prices  secured  on  the  Detroit  contracts. 

At  Milwaukee  considerable  intercepting  construction  has  been  exe- 
cuted in  the  past  five  or  six  years.  Much  of  this  work  was  in  wet  sand 
and  much  of  it  necessitated  the  use  of  compressed  air  with  attendant 
higher  costs. 

The  Milwaukee  sew^er  bids  analyzed  covered  sizes  from  twelve 
inches  to  nine  feet.  Good  competition  was  secured  on  contracts  and 
considering  the  difficult  conditions  of  excavation  found  on  most  of  the 
work  the  costs  are  reasonable  and  consistent. 

In  addition  to  making  the  comparative  study  of  sewer  costs  in 
other  cities,  we  personally  investigated  the  conditions  under  which  the 
North  Side  intercepters  are  now  being  built,  and  prepare  1  independent 
estimates  of  the  fair  cost  of  doing  work  of  that  type.  The  estimates 
made  in  this  way  independently  check  very  well  with  the  actual  cost  in 
other  cities  adjusted  for  Chicago  1925  conditions.  The  results  of  the 
investigations  in  other  cities  and  our  estimates  of  the  reasonable  cost  of 
intercepters  are  shown  graphically  on  Figure  21.  Upon  this  diagram 
we  have  also  shown  by  solid  dots  the  cost  of  five  North  Side  intercepter 
contracts,  let  within  the  last  year  or  two.  It  will  be  noted  that  these 
contract  costs  by  the  Sanitary  District  are  more  than  double  the  prices 
at  which  other  cities  were  able  to  let  contracts  with  prices  adjusted 
to  Chicago  conditions.  The  Chicago  prices  are  in  many  instances  prac- 
tically three  times  the  costs  at  which  the  work  was  let  in  such  cities  as 
Detroit  and  Milwaukee.  Our  estimates  agree  closely  with  the  Sanitary 
District's  estimates  for  future  large  sewers. 

The  excavation  conditions  in  most  sections  of  Chicago  are  at  least 
as  favorable  as  in  any  city  studied.  Our  estimates  assume  conditions 
for  the  central  district  and  the  West  Side,  about  the  same  as  conditions 
-encountered  in  the  North  Side  intercepters  now  under  construction. 


126 


Estimated  Cost  of  West  and  Southzvest  Intercepting  Sewers: 

Using  as  a  basis  the  full  curved  line,  showing  the  cost  of  sewers  of 
various  sizes  shown  on  Figure  21,  the  use  of  which  assumes  that  it  is 
possible  to  build  intercepters  in  Chicago  under  conditions  of  efficiency 
and  cost  comparable  to  those  obtained  in  other  large  American  muni- 
cipalities (adjusted  for  labor  and  material  cost  variations),  we  estimate 
the  cost  of  the  West  side  intercepting  sewers,  including  ten  percent 
for  engineering  and  contingencies  as  $7,890,600. 

Similarly  we  estimate  the  cost  of  the  intercepting  sewers  for  the 
Southwest  plant  at  $4,495,700. 

Based  upon  the  Chicago  Sanitary  District  engineer's  design  as  to 
diameter,  which  is  based  upon  continuation  of  the  present  metering 
policy,  and  upon  the  unit  prices  herein  developed,  the  cost  would  be 
$10,996,100  for  the  West  side  sewers  and  $6,539,500  for  the  Southwest 
Side  intercepter. 

Had  the  estimates  been  computed  using  the  contract  costs  on  inter- 
cepting sewers  recently  let  by  the  Sanitary  District  of  Chicago,  applied 
to  the  same  sewer  quantities  as  in  the  first  and  second  paragraphs  of  this 
section,  the  totals  would  have  been  approximately  $18,210,300  for  the 
West  Side  and  $10,895,500  for  the  Southwest  Side  plants  respectively, 
both  figures  being  more  than  double  what  are  believed  to  be  fair  prices 
for  this  work. 

Period  Covered  by  Design: 

The  intercepting  sewers  as  laid  out  herein  contemplate  1960  condi- 
tions and  as  stated  have  a  designed  capacity  equivalent  to  375  gallons 
per  capita  as  of  that  date,  or  from  450  to  500  gallons  per  capita  as  ap- 
plied to  present  population. 

The  period  for  which  intercepters  should  be  designed  is  dependent 
upon  a  com.parison  of  the  costs  and  practicability  of  providing  capacity 
at  present  for  far  distant  needs  and  the  same  facts  relative  to  providing 
the  additional  capacity  at  such  time  in  the  future  as  the  necessity  occuri,. 
With  sewers  built  in  open  cut  the  cost  of  duplication  usually  becomes 
excessive  due  to  a  more  complete  utilization  of  the  streets  by  utilities  and 
the  increasing  difficulties  due  to  community  growth  and  congestion. 
Such  sewers  are  usually  built  for  long  periods  in  the  future. 

Where  intercepters  are  built  in  tunnels,  somewhat  different  condi- 
tions prevail.  Additional  sewers  can  be  built  in  tunnel  at  a  later  date 
with  little  more  difficulty  and  cost  than  experienced  in  the  original  con- 
struction. With  sewers  in  tunnel  the  period  covered  by  the  design  ac- 
cordingly depends  quite  largely  upon  a  financial  comparison  of  building 
for  ultimate  needs  or  of  building  for  a  shorter  period  with  additional 
capacity  added  later  as  needed. 


127 


We  have  made  a  financial  comparison  of  the  costs  of  intercepting 
sewers  for  the  West  and  Southwest  Side  plants  on  two  bases,  both  of 
which  assume  that  by  1960  it  will  be  necessary  to  double  the  capacity 
now  to  be  provided.  In  one  case  we  have  assumed  that  the  sewer  now 
to  be  built  will  be  constructed  at  its  ultimate  capacity,  that  is,  twice  what 
would  be  required  up  to  1960.  In  the  second  case  we  have  assumed 
the  sewer  to  be  built  now  as  required  for  1960  conditions  and  that  in 
1960  a  duplicate  sewer  will  be  built,  the  cost  of  which  is  reduced  to 
present  worth  and  added  to  the  present  cost  for  comparison  with  the 
first  plan. 

The  cost  comparison  is  as  follows : 

W.  Side      S.  W.  Side 

(1)  Cost  of  sewer  whose  capacity  is  two  times  that 

reqd.  for  1960  conditions  $14,469,400    $  7,746,200 

(2)  Cost  of  sewer  for  1960  conditions   7,890,600  4,495,700 

(3)  Excess  cost  of  (1)  over  (2)  $  6,578,800    $  3,250,500 

(4)  Present  worth  of  cost  of  duplicating  present 

sewer  in  1960  @  5%   1,430,000  815,000 

(5)  Saving  by  postponing  construction  to  1960  $  5,148,800    $  2,435,500 

The  sewer  designed  for  double  the  1960  requirements  would  be  of 
large  diameter  reaching  twenty-four  feet  for  the  West  Side  plant.  The 
costs  used  in  these  estimates  are  secured  from  Figure  21  for  all 
sizes  up  to  twenty  feet.  To  secure  a  unit  for  sizes  above  twenty  feet  a 
curve  of  cost  per  foot  of  diameter  was  platted  and  the  unit  prices  taken 
therefrom. 

Obviously  it  will  be  better  procedure  to  design  conservatively  both 
with  respect  to  period  of  time  and  quantities.  Thirty-five  years  is  be- 
lieved ample  provision  for  time.  Quantities  should  consider  metering 
as  being  ultimately  adopted. 

We  have  given  consideration  to  the  general  routing  of  sewers  pro- 
posed by  the  Sanitary  District  and  are  of  the  opinion  that  approximately 
the  routes  selected  will  be  desirably  followed  when  the  detailed  surveys 
and  plans  are  made. 

We  have  investigated  the  practicability  of  joining  the  West  and 
Southwest  Side  intercepters  about  two  and  one-half  miles  above  the 
tentative  location  of  the  Southwest  Side  plant  but  find  that  the  saving 
thus  effected  would  probably  be  less  than  $100,000.  Its  practicabiHty 
therefore  is  doubtful  and  can  only  be  definitely  ascertained  by  detailed 
investigation  when  the  plans  are  drawn  with  full  information  available. 


128 


PART  XI. 

METHODS  OF  SEWAGE  DISPOSAL  AND  PRACTICABLE 
EFFICIENCIES. 

Why  Sezmge  is  Treated: 

The  water-borne  wastes  of  a  city  are  given  the  general  designation 
of  sewage ;  however,  in  recent  years  the  tendency  has  been  to  restrict 
the  meaning  of  the  word  sewage  to  those  wastes  produced  by  house- 
hold activities  and  to  designate  other  water-borne  impurities  as  indus- 
trial wastes.  In  this  discussion  the  word  sewage  will  be  used  as  inclu- 
sive of  both  domestic  and  industrial  water-borne  wastes. 

Sewage  is  composed  of  more  than  ninety-nine  percent  of  water  and 
less  than  one  percent  of  soluble,  colloidal,  and  solid  constituents.  These 
latter  constitutents,  in  turn,  are  partly  inert  or  stable  and  partly  organic 
or  unstable.  The  unstable  constituents  of  sewage  are  those  which  create 
sight  and  smell  nuisances  in  overtaxed  watercourses,  and  these  unstable 
constituents  may  be  rendered  partially  or  wholly  innocuous  or  inert  by 
subjecting  them  to  proper  processes  of  treatment. 

The  destruction  of  the  unstable  constituents  of  sewage  is  a  bacterial 
function  which  may  be  carried  out  in  a  watercourse  or  in  treatment 
works  in  which  satisfactory  conditions  are  provided  for  bacterial  ac- 
tivity. The  processes  by  which  unstable  sewage  constituents  are  des- 
troyed in  a  stream  are  the  same  as  those  which  result  in  their  destruc- 
tion in  treatment  works. 

An  important  condition  governing  the  bacterial  destruction  of  sew- 
age is  that  of  oxygen  supply,  and  in  general,  it  may  be  said  that  in  the 
presence  of  an  ample  supply  of  oxygen  the  process  of  destruction  will 
proceed  to  completion  in  an  inoffensive  manner,  and  that  in  the  absence 
of  an  ample  supply  of  oxygen,  the  process  of  destruction  will  result  in 
the  production  of  offensive  odors.  In  other  words,  aerobic  conditions 
favor  inoffensive  destruction,  whereas  anaerobic  conditions  favor 
offensive  destruction. 

A  somewhat  analogous  comparison  is  that  of  the  operation  of  a 
steam  boiler  plant.  When  the  furnace  is  properly  operated,  no  smoke 
comes  from  the  attack,  but  when  the  air  supply  is  not  properly  adjusted, 
large  volumes  of  smoke  or  unburned  carbon  come  from  the  stack.  A 
proper  adjustment  of  the  operation  of  the  furnace  eliminates  the  smoke 


129 


nuisance,  whereas  an  ample  supply  of  oxygen  will  go  far  toward  elimin- 
ating the  smell  nuisance  in  the  bacterial  destruction  of  sewage. 

Hozv  Seivage  is  Treated: 

The  various  agencies  involved  in  the  treatment  of  sewage  may  in  a 
general  way  be  classified  as  physical,  chemical,  bacteriological,  and  bio- 
logical, none  of  which  alone  would  suffice.  The  physical  agencies  are 
those  of  screening,  sedimentation,  aeration,  diffusion,  filtration,  evapor- 
ation, etc.  The  chemical  agencies  are  those  involved  in  coagulation, 
sterilization,  and  in  the  mineralization  of  certain  nitrified  products.  The 
bacteriological  agencies  are  those  in  which  the  various  species  of  bac- 
teria are  the  active  agents  in  putrefaction,  fermentation,  nitrification, 
and  denitrification.  The  biological  agencies  are  those  in  which  low 
forms  of  animal  and  vegetable  life  destroy  certain  constituents  of  the 
sewage. 

In  the  various  methods  of  sewage  treatment  in  use  today  practically 
all  of  the  above  agencies  are  involved  to  a  greater  or  less  degree.  Sew- 
age treatment  methods  in  use  today  may  be  classified,  in  a  general  way, 
as  follows :  screening,  sedimentation,  sludge  treatment,  oxidation,  fil- 
tration and  sterilization. 

Sc?'eening: 

As  practiced  in  the  United  States  today,  the  screening  of  sewage 
may  be  classified  on  the  basis  of  coarse  and  fine  separation.  Coarse 
screens  (two  to  four  inch  clear  opening)  have  a  negligible  value  as  a 
purifying  process  and  serve  simply  to  remove  coarse, solids  which  might 
obstruct  passageways  of  pumps  or  be  unsightly  in  treatment  tanks  or  in 
a  stream.  Screens  of  this  character  usually  remain  in  a  stationary 
inclined  position  in  the  pathway  of  the  incoming  sewage  and  may  be 
cleaned  in  position,  or  lifted  for  cleaning. 

Fine  screens  ordinarily  have  a  clear  opening  of  one-eighth  of  an 
inch  or  less  and  usually  rotate  through  the  sewage  stream.  Most  of  them 
are  power-driven  and  are  provided  with  self-cleaning  mechanism.  The 
w^ork  accomplished  by  the  fine  screen  is  intermediate  between  that  ac- 
complished by  coarse  screening  and  very  rapid  sedimentation.  The  fine 
screen  probably  accomplishes  less  in  proportion  to  its  first  cost  and  oper- 
ating cost  than  do  other  methods  of  sewage  treatment,  except  under 
certain  conditions  where  fine  screens  are  particularly  adaptable. 

Sedimentation: 

The  treatment  of  sewage  by  sedimentation  has  for  its  object  the  re- 
duction of  the  strength  of  the  sewage  by  the  removal  of  the  settleable 
solids.    This  is  accomplished  by  passing  the  liquor  through  tanks  at  a 


130 


very  low  velocity,  which  condition  is  conducive  to  a  settling  out  of  a 
portion  of  the  solid  constituents. 

There  are  two  general  types  of  sedimentation  tanks  in  use  today; 
viz.,  those  with  one-story  and  those  with  two-stories.  The  one-story 
tanks  are  further  divided  into  three  classes,  viz.,  those  with  large  capa- 
city for  the  sludge  deposits  which  are  removed  at  infrequent  intervals, 
those  with  small  capacity  for  the  sludge  deposits  which  are  removed  at 
frequent  intervals,  and  those  which  are  provided  with  a  rotating  and 
scraping  mechanism  for  continuous  sludge  removal. 

In  the  first  type  of  one-story  tank  the  incoming  sewage  is  constantly 
in  contact  with  actively  decomposing  sludge  for  considerable  periods  of 
time,  and  it  becomes  infected  with  the  products  resulting  from  the  de- 
composition of  the  sludge.  In  this  type  of  tank  the  sedimentation  and 
sludge  digestion  functions  are  not  separated. 

In  the  second  type  of  one-story  tank,  the  injurious  effect  of  the 
non-separation  of  the  two  functions  is  greatly  reduced  by  frequent  re- 
moval of  the  deposited  sludge,  while  in  the  third  type  of  one-story  tank 
the  separation  of  these  functions  is  practically  complete  due-  to  the  con- 
tinous  removal  of  the  deposited  solids. 

In  the  two-story  type  of  tank  the  separation  of  the  two  functions  is 
accomplished  by  having  a  lower  story  for  sludge  reception  and  digestion 
and  an  upper  story  for  sedimentation.  The  upper  and  lower  stories  are 
so  constructed  that  by  an  arrangement  of  sloping  bottoms,  communi- 
cating slots,  baffles,  and  gas  vents,  the  deposited  solids  enter  the  lower 
compartment  automatically  and  the  digestion  process  may  proceed  with- 
out interfering  with  the  sedimentation  process  and  without  infecting  the 
incoming  sewage.  The  two  processes  thus  proceed  harmoniously,  but 
sludge  withdrawals  must  be  made  at  proper  intervals.  In  many  of  the 
installations  of  this  type,  more  or  less  serious  trouble  from  foaming  at 
the  gas  vents  has  been  experienced  and  corrective  measures  to  date  have 
only  been  partially  successful. 

Sludge  Treatment: 

Solids  removed  from  sewage  by  the  sedimentation  process  are  usu- 
ally designated  as  sludge,  which,  in  composition,  consists  of  from  ninety 
to  ninety-eight  per  cent  water,  and  from  two  to  ten  percent  of  dry  solids. 

The  treatment  and  final  disposal  of  sludge  is  one  of  the  most 
troublesome  problems  of  sewage  disposal.  As  sludge  increases  in 
moisture  content,  the  volume  produced  per  million  gallons  of  sewage 
treated  increases  very  rapidly.  If  the  volume  of  sludge  produced  per 
million  gallons  of  sewage  be  taken  at  1.0  when  the  moisture  content  is 
eighty-five  percent,  the  approximate  volumes  for  higher  moisture  con- 
tent would  be  as  follows:  For  ninety  percent  sludge  1.5,  for  ninety-five 


131 


percent  sludge,  3.0,  and  for  ninety-eight  percent  sludge  7.5  ;  consequent- 
ly those  processes  of  sewage  treatment  which  produce  sludge  of  high 
moisture  content,  impose  the  hurden  of  a  treatment  of  large  bulk  per 
unit  of  dry  solid  content. 

There  are  four  general  methods  of  sludge  treatment  in  use  today, 
viz.,  1st,  lagooning  on  land,  2nd,  pumping  into  scows  and  disposing  of 
it  by  discharging  it  into  deep  water  at  sea.  3rd,  partially  dewatering 
it  on  specially  constructed  sand  filters,  after  which  it  may  be  used  to  fill 
waste  places  or  spread  on  farm  land  and  plowed  in,  4th,  partial  or  com- 
plete dewatering  by  pressing,  centrifuging,  or  drying,  after  which  it 
may  be  used  as  a  fertilizer,  or  for  filling  in  waste  places. 

The  disposal  of  sludge  at  sea  is  obviously  a  method  of  limited  avail- 
ability. A  high  degree  of  dewatering  of  sewage  sludge  through  the  use 
of  presses,  centrifuges,  and  driers,  with  the  intention  of  producing  a 
marketable  fertilizer,  has  as  yet  to  be  demonstrated  as  a  feasible  under- 
taking. The  city  of  Milwaukee,  after  a  thorough  and  painstaking  study 
of  sludge  dewatering  processes  and  the  fertilizing  value  of  sludge  pro- 
duced by  the  activated  sludge  method  of  sewage  treatment,  definitely 
committed  itself  to  the  production  of  fertilizer  sludge  and  now  has  a 
very  complete  dewatering  plant  well  under  construction. 

The  treatment  of  sludge  by  m.ethods  Nos.  1  and  3  has  been  prac- 
tised most  extensively  in  the  United  States  with  varying  degrees  of  suc- 
cess. The  chief  difficulty  which  has  attended  the  use  of  these  methods 
of  sludge  treatment  has  arisen  by  reason  of  the  fact  that  inadequate 
disposal  areas  have  been  provided. 

Oxidation: 

There  are  four  methods  of  sewage  treatment  which  might  be 
termed  '"'finishing  processes,"  and  which  result  in  varying  degrees  of 
stabilization  of  the  soluble,  colloidal  and  solid  constituents  of  the  sew- 
age. In  each  of  the  four  methods  of  treatment,  the  several  constituents 
of  the  sewage  are  changed  from  an  unstable  to  a  stable  condition  largely 
by  bacterial  activities. 

The  four  methods  of  securing  a  finishing  treatment  of  sewage  are 
the  sand  filter,  the  contact  bed,  the  trickling  filter,  and  activated  sludge. 
These  four  methods  of  treatment  vary  widely  in  capacity  per  unit  of 
area,  and  taking  the  capacity  of  the  sand  filter  per  acre  of  area  as  1.0, 
the  relative  capacities  of  the  other  methods  of  treatment  per  acre  of  area 
are  approximately  as  follows :  Contact  beds,  7.0,  trickling  filters  20.0, 
and  activated  sludge  150.0. 

The  sand  filter  when  properly  designed,  constructed,  and  operated 
produces  an  effluent  which  is  clear  and  sparkling,  practically  free  of  sus- 
pended matter,  very  low  in  bacterial  content,  highly  nitrified,  and  with 


132 


an  oxygen  demand  which  is  so  low  as  to  obviate  any  dilution  require- 
ments in  a  stream.  Treatment  of  the  sewage  of  the  Sanitary  District  of 
Chicago  by  sand  filters  preceded  by  clarification  in  settling  tanks  would 
require  at  the  present  time  not  less  than  8,000  acres. 

The  contact  bed  is  an  oxidizing  device  and  consists  of  a  square  or 
rectangular  tank  filled  with  coarse  broken  stone  or  other  suitable  mater- 
ial of  varying  depth  and  operated  ordinarily  on  a  fill-and-draw  plan. 
The  effluent  from  the  contact  bed  is  ordinarily  not  clear  or  well  nitrified, 
has  a  comparatively  high  bacterial  count,  and  an  oxygen  demand  which 
requires  some  dilution  for  stabihty.  Not  less  than  1,200  acres  would  be 
required  to  treat  the  sewage  of  the  Sanitary  District  of  Chicago  fo-r  the 
year  1925,  in  addition  to  clarification  in  settling  tanks. 

The  trickling  filter  is  an  oxidizing  device  similar  to  the  contact  bed 
in' general  construction  but  differing  in  the  method  of  dosing.  The  trick- 
ling filter  is  dosed  by  a  system  of  distribution  pipes  operated  under  a 
head  and  terminating  with  open  spray  nozzles  properly  located  and 
spaced  to  give  uniform  distribution  over  the  entire  surface.  The  sew- 
age is  sprayed  into  the  air  and  falls  on  the  broken  stone  or  other  filtering 
medium  through  which  it  trickles  to  the  underdrains  which  carry  it 
away.  The  cycle  of  operation  consists  of  a  short  dosing  period,  followed 
by  a  short  resting  period.  Trickling  filters  which  are  properly  designed, 
constructed  and  operated  will  produce  effluents  having  a  substantial 
total  bacteria]  count,  a  varying  suspended  matter  content,  a  marked 
reduction  in  oxygen  demand,  and  often  with  a  balanced  oxygen  relation 
if  the  applied  sewage  is  not  particularly  strong.  Not  less  than  400  acres 
of  sprinkling  filters  would  be  required  to  treat  the  sewage  of  the  Sani- 
tary District  of  Chicago  for  the  year  1925,  in  addition  to  a  previous 
clarification  in  settling  tanks. 

The  activated  sludge  process  is  a  comparatively  recent  modification 
of  older  processes,  and  might  be  termed  an  accelerated  bacterial  treat- 
ment in  water.  The  only  sizable  plants  of  this  character  in  operation  in 
the  U.  S.  today  are  the  two  municipal  plants  at  Houston,  Texas.  The 
literature  describing  the  results  of  the  experimental  studies  which  have 
been  made  of  this  process  is  quite  voluminous.  Experimental  plants  of 
this  character,  which  have  been  operated  on  both  large  and  small  scales, 
have  given  very  promising  results,  and  enough  confidence  in  the  pro- 
cess has  arisen  to  justify  its  adoption  for  several  very  large  installations. 

The  principal  operations  in  this  method  of  treatment  are  coarse 
screening,  grit  removal,  fine  screening,  aeration  in  tanks,  sedimentation, 
sludge  reaeration,  return  of  a  portion  of  the  activated  sludge  to  the 
aeration  tanks,  and  treatment  and  disposal  of  the  excess  sludge. 


133 


The  final  effluents  from  this  method  of  treatment  as  produced  ex- 
perimentally and  by  a  small  number  of  municipally  operated  plants  have 
resembled  sand  filter  effluents  with  the  exception  that  they  have  ordi- 
narily not  been  so  completely  nitrified.  The  production  of  an  effluent 
which  will  not  need  dilution  falls  within  the  scope  of  the  possibilities  of 
this  method  of  treatment.  The  degree  to  which  sewage  may  be  rendered 
stable  by  this  method  of  treatment  is  capable  of  some  adjustment.  This 
method  of  treatment  is  one  in  which  careful  and  experienced  supervision 
is  especially  desirable. 

Sterilisation: 

It  is  possible  to  efifect  a  removal  of  from  ninety  to  ninety-five  per- 
cent of  the  total  number  of  bacteria  in  sewage  by  treatment  with  a  steril- 
izing agent.  The  efficacy  of  sterilization  will  be  governed  by  the  size  of 
dose,  the  comminution  of  the  solids  of  the  sewage,  the  distribution  of 
the  sterilizing-  agent,  and  the  thoroughness  and  sufficiency  of  the  con- 
tact of  the  sterilizing  agent  with  the  sewage. 

Experience  with  the  sterilization  of  sewage  to  date  seems  to  indi- 
cate beyond  doubt  that  it  can  be  relied  upon  only  to  provide  a  lessening 
of  the  burden  of  water  purification  where  a  contact  exists. 

Sterilization  destroys  bacteria  but  effects  no  marked  reduction  in 
the  organic  load,  consequently  the  steriHzation  of  sewage  has  no  marked 
effect  on  stream  dilution  requirements. 

Prac tical  E  fficiencies : 

Fine  Screening — Table  29  is  a  partial  list  of  fine  screen  in- 
stallations in  the  U.  S.,  and  an  inspection  of  this  table  will  show  that  the 


TABLE  29. 


PARTIAL  LIST  OF  FINE  SCREENS. 


New  York  City— Dyckman  &  210th  Sts 


Long  Beach,  Cal. 
Daytona,  Fla.  . . . 


Plainfield,  N.  J  

Rochester,  N.  Y.,  Irondequoit  Works 


Bridgeport,  Conn. 


No. 


Dia. 
14' 
14' 
10' 
12' 
12' 
12' 
22' 
22' 
14' 
8' 


Sep. 
Ins. 

3/64 
4/64 
4/64 
24/64 
8/64 
4/64 
1/64 
2/64 
2/64 
5/64 


Indianapolis,  Ind. 
Milwaukee,  Wis. 


12 
8 
1 


6'd.  8'L. 
8'd.  8'L. 
14' 


30  meshes 


6/64 
4/64 


Chicago,  Des  Plaines  River  Plant 


134 


clear  openings  in  the  screens  vary  from  three-eighths  of  an  inch  to  one- 
sixty-fourth  of  an  inch. 

Table  30  shows  the  removal  of  total  suspended  solids  by  fine  screens 
operating  on  municipal  sewage  and  on  industrial  waste.  An  inspec- 
tion of  this  table  will  show  that  from  eight  to  thirty-six  parts  per  mil- 
lion of  suspended  solids  have  been  removed  by  fine  screens  from  muni- 
cipal sewage,  and  103  parts  per  million  from  the  strong  packingtown 
waste  of  Chicago.  The  sewage  which  is  screened  at  the  New  York  city 
plant,  located  at  Dyckman  and  210th  Streets,  is  a  very  fresh  sewage 
(less  than  thirty  minutes  old)  from  a  residential  area. 

The  removal  of  suspended  solids  by  fine  screening  will  be  gov- 
erned by  the  width  of  the  slots,  the  rate  at  which  the  sewage  is  passed 
through  the  screen,  and  the  concentration  and  degree  of  comminution 
of  the  soHds  of  the  sewage. 

The  following  results  have  been  reported  from  the  screen  installa- 
tion at  the  Irondequoit  plant  of  the  city  of  Rochester,  New  York : 
Year  1918 — 6.31  cubic  feet  screenings  per  AI.  G. 
Year  1919 — 6.58  cubic  feet  screenings  per  M.  G. 
Year  1920 — 4.58  cubic  feet  screenings  per  M.  G. 

Sedimentation: 

The  improvement  in  the  quality  of  sewage  resulting  from  sedimen- 
tation treatment  will  be  governed  by  the  concentration  and  comminu- 


TABLE  30. 

SHOWING  REMOVAL  OF  TOTAL  SUSPENDED  SOLIDS  BY 
FINE  SCREENS. 


Width  of 

slots 

Suspended 

Solids 

Source. 

in 

Removed 

Inches 

P.P.M 

% 

(A) 

New  York  City— Dyckman  &  210th  Sts.  3/64 

36 

26.3 

4/64 

20 

16.6 

(B) 

Long  Beach,  California  

2/64 

28 

(C) 

Milwaukee,  Wisconsin   

8/64 

18 

8/64 

8 

(D) 

6/64 

9 

40  meshes 

20 

(E) 

Packinghouse  Industrial  Waste  Tests, 

30  meshes 

103 

18.8 

(A)  Eng.  News-Record,  Vol.  84  p.  171,  1920  by  C.  E.  Gregory. 

(B)  Eng.  News-Record,  Vol.  82,  p.  1012,  1919. 
(O)    6th  Report  Milwaukee  Sew.  Com.,  p.  41. 

(D)  8th  Report  Milwaukee  Sew.  Com.,  p.  72,  73. 

(E)  Report  on  Industrial  wastes  from  the  Stockyards  and  Packingtown  in  Chicago,  Vol.  2, 
■^921,  p.  182. 


135 


tion  of  the  solids  of  the  sewage  treated,  the  detention  period  in  the  tanks, 
and  the  degree  to  which  stored  sludge  interferes  with  the  settling  pro- 
cess. 

Table  31  shows  the  improvement  in  sewage  effecte  1  by  prelim- 
inary sedimentation  as  determined  by  long  and  short  time  tests  on  fif- 
teen of  the  largest  sewage  treatment  works  in  the  United  States.  The 
efficiency  of  these  plants  when  based  on  the  removal  of  total  suspended 
solids  varies  from  twenty-two  percent  to  eighty-six  percent,  with  a 
general  average  of  fifty-five  percent.  The  Proctor  Creek  plant  at  Atlan- 
ta, Ga.,  shows  a  removal  of  eigthy-six  percent,  but  this  result  is  not 
typical  of  plain  sedimentation  for  such  a  large  unit,  and  is  accounted  for 
by  the  fact  that  certain  industrial  wastes  in  the  sewage  react  in  such  a 
way  as  to  produce  a  chemical  precipitation.  The  average  result  for  six- 
teen years  at  Columbus,  O.,  is  fifty-five  percent,  and  the  average  result 
at  Baltimore,  Md.,  for  nine  years  is  fifty-six  percent.  The  average  re- 
sult for  five  years  at  Fitchburg,  Mass  ,  which  is  a  smaller  plant  and 
which  treats  a  fresher  sewage,  is  seventy-three  percent.  It  would 
therefore  seem  that  a  fifty-five  percent  removal  of  total  suspended  solids 
is  a  very  reasonable  expectancy,  and  that  a  better  removal  may  be  se- 
cured where  conditions  are  more  favorable. 

A  study  of  the  settleable  solids  in  daily  composite  samples  of  sew- 
age collected  during  the  past  eight  years  at  Columbus,  Ohio,  has  shown 
that  an  average  of  fifty-one  percent  of  the  total  suspended  solids  is 
settleable  in  a  two-hour  period  in  conical  settling  glasses.  This  result, 
however,  only  applies  to  the  Columbus  sewage. 

Table  31  also  shows  the  improvement  in  sewage  effected  by 
preliminary  sedimentation  on  the  basis  of  the  oxygen  demand.  The  de- 
termination of  oxygen  demand  is  not  a  routine  test  at  any  of  the  sewage 
plants  listed  in  the  table,  consequently  information  of  this  character 
must  be  based  on  short  time  studies.  Oxygen  demand  results  on  eleven 
separate  plants  show  an  average  improvement  of  thirty-five  percent, 
with  extremes  of  three  percent  and  sixty-three  percent.  The  longest 
study  along  this  line  has  been  made  at  Columbus,  Ohio,  where  oxygen 
demand  tests  have  been  a  daily  routine  for  sixteen  years  and  the  sixteen- 
year  average  improvement  by  sedimentation  is  twenty-nine  percent. 
The  Columbus  sewage  is  stale  and  all  of  it  is  pumped,  both  of  which 
conditions  tend  to  reduce  the  efficiency  of  the  sedimentation  treatment. 

It  is  considered  that  an  improvement  of  thirty-five  percent  in  oxy- 
gen demand  is  a  reasonable  expectancy  where  the  factors  affecting  sedi- 
mentation are  average. 


136 


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137 


Sedimentation  and  Sand  Filtration: 

The  treatment  of  sewage  by  sedimentation  and  sand  filtration  in  the 
United  States  today  is,  with  one  exception,  limited  to  small  municipaH- 
ties  and  institutions.  Numerous  small  plants  of  tliis  character  are  in 
service  today  but  definite  information  relative  to  rates  of  treatment 
and  operating  results  is  very  scarce. 

The  largest  sewage  sand  filter  plant  in  the  U.  S.  today  is  the  muni- 
cipal plant  at  Worcester,  Mass.,  where,  during  the  year  1923,  64.7  acres 
of  sand  filters  were  operated  at  an  average  daily  yield  of  55,000  gallons. 
A  portion  of  the  sewage  of  Worcester  is  treated  by  sand  filtration  by 
reason  of  the  fact  that  natural  sand  areas  are  available. 

The  average  results  secured  at  Worcester,  during  1923,  by  the  sand 
filtration  treatment  were  as  follows : 

Reduction  in  total  albuminoid  ammonia,  89%. 
Reduction  in  total  suspended  solids,  100%. 
Reduction  in  total  oxygen  consumed,  90%. 
These  average  results  represent  a  very  high  degree  of  treatment, 
with  probably  a  negative  dilution  requirement. 

Sedimentation  and  Sprinkling  Filters: 

The  sprinkling  filter,  almost  without  exception,  is  dosed  with  clari- 
fied sewage  and  the  effluent  from  the  filter  is  often  given  a  final  clarifica- 
tion before  being  discharged  into  a  watercourse.  The  improvement 
effected  by  tanks  and  sprinkling  filters  with  and  without  final  sedimen- 
tation is  shown  in  Table  32. 

An  inspection  of  this  table  will  show  that  of  the  total  amount  of 
suspended  solids  removed  by  tanks  and  sprinkling  filters,  eighty-five 
percent  is  removed  by  the  tanks  and  fifteen  percent  by  the  filters.  In 
the  reduction  of  the  oxygen  demand  by  tanks  and  filters,  the  results 
in  Table  32  show  that  of  the  total  reduction,  forty-five  percent  comes 
from  the  tank  treatment  and  fifty-five  percent  from  the  sprinkling  filter 
treatment.  If  the  two  Atlanta  and  the  Baltimore  results  are  eliminated, 
the  ratio  is  for  tanks  forty  percent  and  for  sprinkling  filters  sixty  per- 
cent. 

A  further  inspection  of  this  table  will  show  that  the  reduction  in 
oxygen  demand  in  parts  per  million  by  tanks,  with  Baltimore  results 
excluded,  will  vary,  on  the  basis  of  average  results,  from  thirty  to  sixty 
parts  and  that  the  reduction  in  oxygen  demand  by  sprinkling  filters,  with 
the  Atlanta  results  excluded,  will  vary,  on  the  basis  of  average  results, 
from  seventy  to  ninety  parts.  The  reduction  by  combined  treatment 
in  tanks,  sprinkling  filters,  and  final  settling  basins,  with  the  Atlanta 
results  excluded,  will  vary,  on  the  basis  of  average  results,  from  ninety 


138 


to  135  parts.  From  a  study  of  the  best  results  obtainable,  and  as  re- 
corded in  Table  32,  a  reasonable  expectancy  from  tanks,  sprinkling 
filters  and  final  settling  basins  is  as  follows : 

Removal  of  total  suspended  solids,  75%  average  result. 
Reduction  in  oxygen  demand,  85%  average  result. 

Reduction  in  oxygen  demand  in  p.p.m.,  130  average  result. 
Data  relative  to  the  reduction  in  the  number  of  bacteria  by  this 
method  of  treatment  is  limited  to  the  total  counts  which  have  been  made 
at  the  Baltimore  sewage  works  for  a  number  of  years.  Average  values 
for  a  period  of  nine  years  from  1912  to  1920,  inclusive,  at  the  Baltimore 
sewage  works  are  as  follows : 

Reduction  in  the  total  count  on  plain  agar,  67% 
Reduction  in  acid  forming  bacteria,  90% 

TABLE  32. 


SHOWING  IMPROVEMENTS  EFFECTED  BY  TANKS  AND  SPRINKLING 
FILTERS  WITH  AND  WITHOUT  FINAL  SEDIMENTATION. 


Location 

By 
Tanks 

By 
Sprinklers 

By 
Basins 

Atlanta  .... 

..(B) 

37 

23 

60 

Total  Suspen 
Solids  Remo 
in  %  of  Tot 

Columbus  . . 
Fitchburg  . . 
Lexington  . 
Baltimore  . 

..(B) 
..(B) 
..(A) 
..(A) 
...(A) 

70 
55 
79 
60 
56 

13 
10 

4 
16 

6 

3 
5 
16 

83 
65 
86 
71 
78 

.  .  (B) 

63 

31 

94 

Dem 
ction 
f  Tot 

Atlanta  . . . . 
Columbus  . 

..(B) 
..(B) 

62 
25 

31 

.  55 

93 
80 

Oxygen 
Redu 
in  %  0 

Fitchburg  . . 

..(A) 

38 

49 

87 

Lexington  . 
Baltimore  . . 

...(A) 
..(A) 

40 
3 

67 

49 

10 

89 
80 

a  § 

Atlanta  .  . . 

..(B) 

32 

16 

48 

a  1  S 

..(B) 

39 

19 

58 

.2  Q  a 

Baltimore  . 

..(A) 

4 

76 

11 

91 

Columbus  . 

..(B) 

39 

87 

126 

o 

Lexington  . 
Fitchburg  . 

...(A) 
. .  .  (A) 

57 
59 

75 

71 

inc. 

128 
133 

(A)    Tanks,  sprinkling  filters  and  final  settling  basins. 


(B)    Tanks,  and  sprinkling  filters. 


139 


Sedimentation  and  Contact  Beds: 

Accurate  operating  results  for  tanks  and  contact  beds  are  very 
limited  :  however,  in  Table  33  are  shown  the  analytical  data  secured 
by  the  U.  S.  Public  Health  Service  from  a  ten  to  twelve  days'  study  of 
the  Alliance,  Ohio  and  Canton,  Ohio,  sewage  w^orks  which  employ  this 
method  of  treatment.  The  average  results  from  these  two  plants  show 
that  the  improvement  effected  by  this  method  of  treatmeni"  was  as 
follows : 

Reduction  in  total  suspended  soHds,  85%. 

Reduction  in  oxygen  consumed,  71%. 

Reduction  in  oxygen  demand,  80%. 
The  contact  beds  of  these  two  plants  treat  between  600,000  and 
700,000  gallons  per  acre  per  day,  which  is  about  one-third  of  the  volume 
that  can  be  treated  satisfactorily  by  a  sprinkling  filter  per  acre  per  day. 

Activated  Sludge: 

It  is  difficult  to  set  a  standard  of  practical  efficiency  for  the  acti- 
vated sludge  treatment  of  sewage  without  relying  considerably  on  re- 
sults secured  by  numerous  experimental  installations.  Little  doubt 
exists  today  as  to  the  soundness  of  the  principles  involved,  but  some 
doubt  does  exist  relative  to  the  methods  and  appliances  proposed  for 
carrying  out  these  principles.  Machinery  plays  a  greater  part  in  this 
method  of  sewage  treatment  than  in  any  other  method  in  common  use; 
also  a  very  extensive  air  distribution  system  must  be  used,  which  com- 
prises valves,  pipes  of  many  sizes,  and  in  all  cases  final  air  outlets  which 
are  extremely  small.  The  coefficient  of  dependability  of  some  features 
of  this  process  may  be  said  to  be  somewhat  uncertain ;  however,  the 
several  features  of  this  process  have  been  very  carefully  investigated  by 
so  many  competent  chemists  and  engineers  and  their  conclusions  have 
been  so  well  founded  that  its  adoption  as  a  practical  method  of  sewage 
treatment  seems  to  be  based  on  sound  judgment. 

In  Table  33  will  be  found  analytical  data  secured  from  a  ten 
to  twelve-day  study  of  the  north  side  and  south  side  plants  at  Houston, 
Texas,  analytical  results  secured  from  a  two  years'  operation  of  the 
same  plants,  analytical  results  of  a  ten  to  eleven-day  study  of  the  plants 
at  San  Marcos,  and  Sherman,  Texas ;  also  results  of  twenty-three 
months  of  operation  of  the  Des  Plaines  River  plant  of  the  Sanitary 
District  of  Chicago.  The  Des  Plaines  plant  has  been  operated  on  a  com- 
bined routine  and  experimental  basis,  consequently  the  results  are  prob- 
ably not  such  as  might  be  secured  if  it  had  been  operated  with  a  single 
purpose  in  view. 


140 


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142 


Omitting  from  consideration  the  results  from  the  Des  Plaines  and 
Sherman,  Texas,  plants,  the  results  recorded  in  Table  33  indicate 
an  improvement  from  this  method  of  treatment  as  follows : 
Removal  of  suspended  solids,  94%. 
Reduction  in  oxygen  consumed,  81%. 
Reduction  in  oxygen  demand,  92%. 
The  north  side  and  south  side  plants  at  Houston,  Texas,  treat  ap- 
proximately six  million  and  one  and  one-half  million  gallons  per  day,  re- 
spectively.  The  San  Marcos,  Texas,  plant  treats  approximately  200,000 
gallons  of  sewage  per  day. 

The  use  of  the  activated  sludge  process  for  the  treatment  of  pack- 
ing and  stockyards  sewage  has  been  tested  experimentally  by  the  Sani- 
tary District  of  Chicago,  and  the  improvement  elfected,  as  based  on 
data  recorded  on  pages  47  and  134  of  the  Report  on  Industrial  Wastes 
from  the  Stockyards  and  Packingtown  in  Chicago,  Vol.  2,  1921,  San. 
Dist.  of  Chicago,  is  as  follows : 

Removal  of  total  suspended  solids,  91%. 
Reduction  of  oxygen  demand,  96%. 
Reduction  of  organic  nitrogen,  83%. 

Warm  Weather  Efficiencies: 

In  view  of  the  fact  that  during  warm  weather  there  is  an  accelera- 
tion of  bacterial  activities  both  in  polluted  streams  and  in  bacterial  pro- 
cesses of  sewage  treatment,  it  is  evident  that  dilution  requirements  in  a 
stream  during  warm  weather  are  at  the  maximum,  and,  for  the  same 
reason,  it  would  seem  that  the  efficiency  of  sewage  treatment  would  be 
higher  wherever  bacterial  processes  are  involved. 

A  study  of  the  average  monthly  efficiencies  at  the  Baltimore  works 
for  a  period  of  nine  years,  the  sand  filtration  treatment  at  Worcester, 
Mass.,  for  1923,  and  the  Columbus  works  for  the  year  1913,  indicate 
that  the  average  efficiency  for  June,  July,  August  and  September  is 
above  the  average  efficiency  for  the  year  in  the  following  amounts : 

Baltimore,  four  percent ;  Worcester,  three  percent ;  Columbus, 
three  percent. 

An  average  efficiency  for  the  warm  weather  months  of  the  year,  of 
three  percent  above  the  average  annual  efficiency  is  a  reasonable  assump- 
tion for  sand  filter,  contact  bed,  sprinkling  filter  and  activated  sludge 
treatment. 

Conclusion  on  Efficiency: 

In  consideration  of  treatment  works  for  the  largest  sewage  dis- 
posal plant  in  the  world,  we  believe  we  are  warranted  in  expecting  the 
best  of  operating  results.    We  conclude  that  it  will  be  practicable  to 


143 


secure  the  following  net  efficiencies  in  the  proposed  Sanitary  District 
plants,  in  the  warm  or  critical  season  of  the  year,  expressed  in  percentage 
of  the  biochemical  oxygen  demand  removed  from  the  sewage  compared 
to  sew^age  as  delivered  before  treatment. 

Tankage,  35%^. 

Tanks  and  Sprinkling  Filters,  88%. 

Activated  sludge  on  Domestic  Sewage,  92%. 

Activated  sludge  on  Stock  Yards  waste,  95%. 

Applicability  of  Other  Means  of  Sewage  Disposal: 

The  subject  of  sewage  disposal  for  Chicago  would  not  be  complete 
without  consideration  of  certain  means  for  sewage  disposal  that  have 
been  extensively  used  abroad  but  which  are  not  considered  to  be  adapted 
to  the  local  situation  at  Chicago,  particularly  when  taking  into  consider- 
ation the  expenditures  that  the  Sanitary  District  has  already  made.  We 
believe  it  v^^ill  be  useful,  briefly  to  outline  these  methods  of  disposal 
and  to  show  why  it  would  not  be  practicable  or  economical  to  adopt 
them. 

Broad  Irrigation: 

The  oldest  method  of  sewage  purification  is  the  disposal  of  the  sew- 
age upon  farm  or  garden  land,  commonly  called  Broad  Irrigation.  The 
sewages  of  Berlin  and  Paris  are  thus  treated,  and  the  method  has  been 
extensively  used  in  Germany,  France  and  England. 

Inapplicable  to  Chicago  Conditions: 

If  Broad  Irrigation  should  be  adopted  for  Chicago,  about  60,000 
acres  or  ninety-three  square  miles,  would  be  required  under  the  average 
rate  of  application  to  land  as  practiced  in  England,  where,  in  general, 
available  land  contains  more  or  less  clay. 

If  sandy  lands  could  be  found,  similar  to  that  available  for  sewage 
disposal  at  Berlin,  about  25,000  acres  or  thirty-nine  square  miles,  would 
be  required.  It  is  believed  that  no  such  large  areas  are  available,  with- 
out carrying  the  sewage  a  long  distance  from  Chicago. 

No  surface  soils' of  a  sandy  nature  are  available  nearer  to  Chicago 
than  the  east  line  of  Gary,  which  is  approximately  forty  miles  distant 
from  the  Chicago  loop  district.  A  sufficient  area  could  probably  be 
found  east  of  Gary,  but  the  land  is  very  rough  and  large  expenditures 
in  grading,  or  in  pumping,  would  be  required  to  make  it  useful. 

A  sewer  about  twenty-five  feet  in  diameter  would  be  required  to 
accommodate  the  present  total  sewage  of  the  Sanitary  District.  This 
sewer  would  cost  about  $1,500,000  per  mile.  Approximate  estimates 
indicate  that  the  initial  investment  in  an  outlet  sewer  and  pumping 


144 


works  alone  would  exceed  the  cost  of  the  intercepting  sewers  and  the 
more  modern  methods  of  sewage  disposal,  for  which  we  have  previously 
estimated  the  costs.  In  addition  it  would  be  necessary  to  purchase  the 
lands  and  put  them  into  condition  to  receive  sewage. 

Site  Below  Jolict: 

Before  the  drainage  canal  was  built  the  suggestion  was  made  to 
carry  the  Chicago  sewage  through  a  tunnel  and  dispose  of  it  by  gravity 
upon  lands  adjacent  to  the  Des  Plaines  River  below  Joliet.  This  might 
have  been  possible  with  the  quantities  of  sewage  produced  by  Chicago 
thirty  or  forty  years  ago.  At  the  present  time  it  would  not  be  possible 
to. find  an  acreage  sufficiently  large  to  treat  the  sewage  by  Broad  Irriga- 
tion, delivering  the  sewage  by  gravity  flow.  Lands  m.ight  be  found  to 
which  the  sewage  could  be  pumped. 

The  land  at  this  location  is  of  a  sandy  and  gravelly  nature.  It 
would  probably  be  well  adapted  to  sewage  farming.  Rough  estimates 
indicate  that  the  cost  of  development,  including  tunnel  and  pumping, 
would  not  be  less  than  the  figures  previously  given  covering  sewage 
farming  on  the  lands  east  of  Gary.  Therefore  the  costs  would  materially 
exceed  the  costs  of  work§,  herein  elsewhere  estimated. 

Broad  Irrigation  Not  Practicable: 

There  are  other  and  more  important  reasons  why  broad  irrigation 
would  not  be  applicable. 

(a)  Sewage  farming  is  viewed  with  disfavor  by  American  health 
authorities,  as  dangerous  to  public  health. 

(b)  Climatic  conditions  arc  much  less  favorable  in  this  region 
than  in  Western  Europe  by  reason  of  the  severe  winters. 

•  (c)  The  American  public  is  less  tolerant  of  local  nuisances  than 
the  European  public,  and  is  less  inclined  to  properly  maintain  its  sewage 
works.  A  sewage  farm  would  be  an  intolerable  nuisance  unless  well 
operated. 

Other  Disposal  Methods: 

We  have  herein  elsewhere  mentioned  contact  beds  and  sand  filters  as 
means  for  secondary  purification,  which  have  been  more  or  less  exten- 
sively usd  by  small  cities  and  large  public  institutions.  Either  of  these 
methods,  by  reason  of  the  large  areas  required,  would  necessitate  large 
expenditures  for  intercepting  sewers  to  carry  the  sewage  to  more  or 
less  distant  and  remote  locations.  We  believe  that  the  relative  areas 
required,  as  stated  elsewhere  in  this  report,  are  sufficient  to  indicate 
their  higher  cost  as  compared  to  the  methods  of  sewage  purification 
upon  which  we  have  prepared  detailed  estimates. 


145 


PART  XII. 

SEWAGE  DISPOSAL  COSTS  IN  OTHER  CITIES. 

Chicago,  through  the  Sanitary  District,  is  undertaking  a  great 
sewage  disposal  program.  To  date,  although  the  second  Jargest  city  in 
the  United  States,  it  has  not  constructed  and  operated  disposal  works 
of  magnitude  commensurate  with  its  wastes. 

Certain  other  cities  have  had  considerable  experience  in  the  con- 
struction of  sewage  disposal  works  of  the  types  generally  considered  as 
applicable  to  Chicago  conditions.  The  costs  of  these  works,  are  capable 
of  analysis  considered  as  units,  so  that  knowing  the  number  of  units  of 
each  plant  item  required,  costs  of  similar  plants  in  individual  cities  may 
be  compared.  If  in  this  comparison  the  varying  costs  of  labor  and 
materials  are  brought  to  a  common  basis,  the  results  are  quite  reliable 
as  an  indication  of  fair  costs  under  the  conditions  pertaining  to  that 
basis. 

In  order  that  we  might  have  first  hand  information  as  to  the  costs 
of  construction  and  operation  of  the  larger  sewage  disposal  plants  of 
the  country,  and  have  sufficient  familiarity  with  the  plants  and  their 
operations  to  interpret  the  cost  of  construction  and  operations  and  trans- 
late them  to  Chicago  conditions,  we  visited  the  more  important  plants, 
including  Baltimore,  Cleveland,  Philadelphia,  Albany,  Indianapolis  and 
Milwaukee.  At  all  of  these  plants  we  were  courteously  extended  all  of 
the  available  information  relative  to  cost  of  construction  and  operation. 
This  information  has  been  supplemented  by  other  cost  data  in  our 
possession. 

We  gave  particular  attention  to  the  costs  of  construction  and  cost 
of  operating: 

(a)  Tankage  plants. 

(b)  Tankage  and  trickling  filters. 

(c)  Activated  sludge  plants. 

(d)  Pumping  Stations. 

which  types  of  construction  must  necessarily  be  included  in  any  compre- 
hensive study  of  the  Chicago  situation.  We  also  investigated  sewer 
construction  and  costs  in  a  great  many  cities. 

Adjustment  of  Costs  to  Chicago  1925  Basis: 

In  each  of  the  several  cities  visited  to  secure  costs  of  sewer  and 
sewage  disposal  plant  construction  the  costs  of  labor  were  found  to  vary. 


146 


It  was  also  found  that  the  construction  studied  in  the  several  cities  had 
been  executed  at  different  time  periods  and  accordingly  under  varying 
price  level  conditions. 

In  adapting  these  data  for  use  in  studying  reasonable  Chicago  con- 
struction costs,  it  was  accordingly  necessary  to  make  two  adjustments, 
viz : 

(a)  For  location. 

(b)  For  time. 

The  first  adjustment  was  made  by  studying  the  labor  costs  for  the 
various  types  of  labor  involved  in  each  construction  project  and  ascer- 
taining the  weighted  average  relation  of  those  costs  in  the  city  being 
studied  to  those  prevailing  in  Chicago.  This  resulted  in  securing  a  fac- 
tor wliich  applied  to  the  costs  in  the  city  studied,  would  reasonably  indi- 
cate the  costs  in  Chicago  as  of  the  same  period.  In  cities  for  which 
there  were  no  printed  data  available  as  to  labor  costs  inquiry  was  either 
made  by  letter  or  the  costs  prevailing  in  the  nearest  city  for  which  the 
data  available  were  used.  Table  34  shows  the  rates  for  skilled 
construction,  skilled  operating  and  common  labor  in  a  number  of  cities 
expressed  in  percentage  of  Chicago  rates  for  the  same  classes  of  labor. 
The  comparison  is  as  of  1925. 

The  adjustment  for  time  was  made  by  using  the  United  States 
Department  of  Labor  data  relative  to  fluctuations  in  prices  for  building 
materials,  and  the  prices  paid  by  the  City  of  Chicago  for  skilled  con- 
struction labor,  common  labor,  skilled  operating  labor  and  engineering 
or  supervisory  services. 

Figure  22  shows  diagrammatically  the  cost  index  of  building 
materials  from  1913  to  1925,  based  on  United  States  Department  of 
Labor  data. 

Figure  23  shows  the  variations  in  the  rates  paid  by  the  City  of 
Chicago  for  various  classes  of  labor  entering  into  the  construction  and 
operation  of  sewers  and  sewage  disposal  works. 

In  the  application  of  these  data  to  the  various  types  of  construction 
it  was  necessary  to  estimate  approximately  the  percentages  of  materials 
and  labor  and  the  relative  proportions  of  each  class  of  labor  required. 

All  time  corrections  were  computed  as  of  the  date  of  letting  con- 
tracts. In  some  cases  where  several  contracts  were  involved  the  result- 
ing time  factor  w'as  a  weighted  composite  of  the  individual  contracts. 
In  case  of  defaulting  of  the  original  contractor  and  the  reletting  of  the 
work  the  latter  date  and  contract  cost  were  used  for  the  date  and  pay- 
ments under  the  original  contract. 


147 


Co=»T  \noex  op  Bu\ud\ng  MATC^IAU^) 
U.  e>.  Oh.p>-t  of  Labor. 
loiN-bm  too  % 


Figure  22. — Cost  index  of  building  materials. 


WS.-r*.-r>o»4  OT=^«.Jfc.-r 

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!qi4.    T^Ts  ioTTiqii     i^iq    ii-zo   iqii     nrz  ii-za  1925 

Figure  23. — Variations  in  skilled  and  unskilled  labor  rates  in  Chicago,  based 
on  City  of  Chicago  records,  1913  being  100%. 


148 


TABLE  34. 

TABLE  SHOWING  %  RATIO  OF  SALARIES  PAID  TO  SKILLED  AND 
UNSKILLED   LABOR   IN   VARIOUS  CITIES,   BASED  ON 
CHICAGO  PRICES  IN  1925  BEING  100%. 

Common  Skilled  Labor 

City  Labor  Construction  Operation 

Albany,  N.  Y  

Atlanta,  Ga  

Baltimore,  Md  

Boston,  Mass  


Columbus,  Ohio  . 
Fitchburg,  Mass. 
Houston,  Texas  . 
Indianapolis,  Ind. 
Lincoln,  Neb.  .  . . 
Milwaukee,  Wis. 
Marion,  Ohio  . . . . 
New  Orleans,  La. 


Rochester,  N.  Y. 
Syracuse,  N.  Y. . 
Urbana,  111  


Detroit, 


85.0 

92.5 

87.0 

36.4 

78.8 

61.8 

48.5 

96.0 

68.0 

78.8 

84.5 

85.1 

100.0 

100.0 

100.0 

106.0 

99.5 

103.8 

48.5 

88.4 

83.3 

60.6 

84.1 

81.6 

48.5 

96.6 

81.0 

54.5 

95.9 

95.5 

40.0 

to.o 

<  Z.b 

ol.v 

<y.o 

O'l.O 

'7Q  a 

60.6 

81.1 

8^.0 

60.6 

92.5 

88.0 

60.6 

86.4 

75.7 

84.9 

91.5 

86.9 

84.9 

84.7 

80.5 

66.6 

92.1 

84.0 

48.5 

73.8 

73.8 

66.6 

87.8 

70.0 

66.6 

87.8 

70.0 

72.8 

93.5 

95.0 

106.0 

116.0 

102.7 

64.6 

87.0 

76.8 

Tankage  Plants: 

The  largest  tankage  plants  of  the  country,  which  at  the  present 
time  are  operating  without  secondary  treatment,  are  those  of  Cleveland 
(Westerly  Plant),  Rochester,  (Irondequoit  Plant),  Philadelphia  and 
Albany.  In  each  of  these  plants  we  ascertained  the  facts  relative  to 
first  costs,  date  of  construction,  and  the  costs  of  operation. 

The  data  relative  to  construction  costs  are  shown  on  Table  35. 
Inasmuch  as  these  costs  were  incurred  during  a  period  of  rapid  and 
great  fluctuations  in  prices,  all  of  these  costs  have  been  reduced  to  the 
basis  of  1925  conditions,  and  then  further  adjusted  for  the  difference  in 
conditions  prevailing  in  -each  of  these  towns  as  compared  to  Chicago. 

~  The  costs  reduced  to  the  1925  Chicago  basis  average  $5.00  per 
capita  and  $30,750  per  million  gallons  daily  capacity. 

At  the  bottom  of  this  table  are  shown  similar  figures  for  the  Calu- 
met plant  of  the  Sanitary  District  of  Chicago.    The  per  capita  cost  of 


149 


the  Calumet  plant  is  $26.40  and  the  cost  per  M.G.D.  capacity  is  $86,000. 
The  tabulation  of  bids  on  the  Calumet  plant  shows  that  the  concrete  for 
the  tanks,  28,000  cubic  yards,  was  let  at  a  price  of  $64.00  per  cubic  yard 
exclusive  of  reinforcing  steel.  The  steel,  3,000,000  pounds,  was  let  at  a 
unit  price  of  twenty-three  cents  per  pound.  The  concrete  complete, 
therefore,  was  let  at  a  unit  price  exceeding  $85.00  per  cubic  yard.  The. 
work  included  thirty  tanks  permitting  multiple  use  of  forms  and  plant. 

In  making  the  comparison  of  construction  costs  for  utilization  in 
preparing  estimates  for  Chicago  plants  yet  to  be  built,  all  figures  w^ere 
reduced  insofar  as  possible  to  a  unit  volume  or  capacity  basis.  On  tank- 
age plants  for  example  the  comparison  is  based  upon  the  displacement 


TABLE  35. 

CONSTRUCTION  COSTS  OF  TANKAGE  PLANTS  (2  Story  Type) 
INCLUDING  SCREENING,  GRIT  CHAMBERS  AND  SLUDGE  DISPOSAL. 


• 

Ition 
Led  for 

Year  Built 

ity  de- 
L  for  MGD 

ruction 

rsion 

Construction  Costs 

a'm 

O  <D 

Quant 
signed 

Actual 

L/Onsil 

Cost 

Conve 
Facto: 

Based  on  Chicago 
Prices  of  Material 
and  Labor,  1925. 

Per 

Per 

Total 

Total  Capita 

M.G.D. 

♦♦Cleveland  288,000 

1916-23 

36 

$  944,130 

1.06 

$1,000,000  ?3.47 

$27,800 

(Westerly) 

Rochester,  N.  Y.. 200,000 

1916 

34 

500,250 

1.87 

935,000  4.67 

27,500 

(Irondequoit) 

(a)  Philadelphia. 300,000 

1917-23 

60 

1,698,770 

1.23 

2,085,000  6.95 

34,800 

Albany   156,000 

1915 

30 

443,080 

2.03 

901,000  5.77 

30,000 

5.22 

30,025 

Weighted  average 

5.00 

30,750 

Chicago,  Calumet 

Plant   179,000 

1920-23  55.0 

*$5,207,569 

.91 

*$4,747,000  $26.40 

$86,000 

*Corrected  for  1  M.  G.  D.  activated  sludge  and  4.44  acre  ft.  of  filters  and  for  land. 
**No  sludge  drying  beds — Cost  adjusted  on  basis  of  1919. 

(a  One-third  built  under  original  contract — two  thirds  under  new  contract  let  in  July,  1920. 
No  Intercepters  or  Pumping  Stations  included. 


volume  of  both  the  flow  and  digestion  chambers  in  order  to  eliminate 
the  variations  in  detention  periods,  sludge  storage  per  capita,  strength 
and  amount  of  sev^age  and  the  momentary  under  or  overbuilt  condition 
of  the  plant.  The  average  and  weighted  average  of  the  costs  for  each 
part  of  the  plants,  such  as  screens,  grit  chambers,  tanks,  sludge  beds, 
etc.,  were  secured  for  use  in  estimating  reasonable  construction  costs 
for  Chicago  conditions.    The  detailed  data  are  shown  in  Table  38. 


150 


Weighted  averages  were  computed  in  order  that  the  relative  effect  of 
size  of  units  upon  cost  might  be  taken  into  consideration. 

Table  36  shows  the  operating  costs  of  these  Imhoff  tank  plants.  It 
shows  also  the  cost  of  operating  the  separate  digestion  tanks  at  Balti- 
more in  which  the  operating  costs  are  excellently  sub-divided  so  that  the 
,tank  and  sludge  operations  are  available.  We  have  also  shown  the 
facts  relative  to  the  Calumet  plant  of  the  Chicago  Sanitary  District  on 
this  table. 


TABLE  36. 

OPERATING  COSTS  OF  TANKAGE  PLANTS. 


Liting 
ion 

bo 
d 

o. 

Operating  Costs  re- 

ar Co 
iered 

ntribi 
pulat 

eated 

nual 

erati] 
sts 

avers 
ctor 

duced  to 
asis — ; 

Chicago  1925 
Labor  Only 

o  o 

c  a  o 

O  03 

Changed 

per 

per 

City 

Total 

Total" 

Capita 

M.G. 

♦Cleveland   

1924 

87,000 

4,800 

$  33,847 

0.975 

$  32,929 

$  .378 

$6.85 

Rochester  .... 

1919 

240,000 

12,050 

30,809 

1.48 

45,625 

.190 

3.78 

'♦Philadelphia  .. 

1924 

117,000 

8,100 

28,420 

1.31 

37,280 

.319 

4.61 

Albany   

1920 

104,358 

5,220 

21,127 

1.29 

27,202 

.261 

5.21 

Baltimore  .... 

1923 

690,000 

20,100 

75,842 

1.07 

81,352 

.135 

4.04 

Average 

.256 

4.90 

Weighted  Ave. . 

.192 

4.47 

Calumet,  Chicago 

Sanitary  Dist. 

1924 

90,000 

10,600t 

$199,567t 

$199,567t 

$2.22 

$18.82 

*No  sludge  drying  beds — sludge  pumped  to  Lake  Erie. 
**No  sludge  drawn  to  beds  in  1924. 

tDeducted  1180  M.  G.  estimated  sljidge  operation  @  $21.95  =  $25,800. 


At  the  Westerly  Cleveland  plant  the  sludge  instead  of  being  dried 
on  beds  is  discharged  into  the  outlet  sewer.  The  total  operating  ex- 
penses of  this  plant  were  credited  with  the  cost  of  chlorination  which  is 
practiced  during  the  summer  season. 

At  Philadelphia  the  plant  is  provided  with  sand  sludge  drying  beds 
but  no  sludge  was  removed  during  1924. 

Baltimore,  a  separate  sludge  digestion  type  of  plant,  has  the  lowest 
per  capita  expenditure  for  tank  and  sludge  bed  treatment  of  any  of  the 
large  plants  studied. 

It  will  be  noticed  that  the  weighted  average  cost  of  operating  Im- 
hoff tank  plants  adjusted  to  Chicago  1925  conditions  was  19.2  cents  per 
capita  and  $4.47  per  million  gallons  treated.  The  Calumet  plant  in 
Chicago,  built  in  1920,  with  costs  adjusted  for  a  small  experimental 
plant  and  reduced  to  1925  conditions  on  the  same  basis  as  the  other 


151 


plants  was  $2.22  per  capita  and  $18.82  per  million  gallons.  The  per 
capita  cost  was  ten  times  the  average  of  the  other  plants,  and  the  cost 
per  M.  G.,  due  to  the  higher  per  capita  use,  was  still  over  four  times  the 
average  and  nearly  three  times  the  highest  of  the  other  plants. 

Comparative  cost  of  construction  of  these  plants  is  shown  dia- 
grammatically  on  Figure  24. 

The  operating  costs  of  Tankage  plants  in  cities  other  than  Chicago 
vary  from  13.5  cents  to  nearly  38  cents  per  capita,  adjusted  to  the 


HecivL3  linee  indicafe  1000  DoUart>  per  M.G.D 
LiQh'i       ■•  -        Dollars  perCapifa 

UnisHoded  cir-<r o s.  or-e  cor-r-eci+(or-\'3 
■^or-  Coicaqo  cood  i-Viori<s 
'oHode  or-eQ<5  ore  oc+uol  Cos-V 


Plants 


Figure  24. — Cost  of  constructing  Imhoff  tank  disposal  plants,  based  on 
1925  Chicago  conditions. 


152 


Chicago  1925  basis  and  from  $3.78  to  $6.85  per  million  gallons  treated 
referred  to  the  Chicago  1925  price  basis.  These  facts  relative  to  operat- 
ing costs,  together  with  the  operating  cost  of  the  Calumet  plant  of  the 
Chicago  vSanitary  District  are  shown  diagrammatically  on  Figure  25. 

Opcra+ion       Maw^dnanca.  -   Dollars    per  Million  Gallons. 

O  cn  5  ui  o 


ROCHESTCR 


Balximorc. 


Philaoc.i_p>mia 


No  sludqe  rzrr\o^e.c 


ho   eludgc  beds 


Crediteci  With 
Sluolg«Plan+ 


rr-ioU  Ac+ivated 
Operation 


o  -  M  o» 

Opero+ion  Sk  W\Q\r\\Q,rtariCC-   Dollars  per  Cap! fa 

Figure  25. — Cost  of  operating  tank  disposal  plants,  based  on  1925 
Chicago  conditions. 

Heavy  lines  indicate  $  per  million  gallons. 
Light  lines  indicate  $  per  capita. 

Imhoif  Tank^  Sprinkling  Filter  Plants: 

In  a  manner  similar  to  that  just  outlined  we  investigates!  the  costs 
of  construction  and  operation  of  eight  (8)  Imhoff  tank  sprinkling 
filter  plants,  all  cost  being  reduced  to  the  1925  Chicago  basis. 

Insofar  as  possible  the  costs  of  construction  of  these  plants  were 
likewise  subdivided  into  the  various  units  of  the  plants,  such  as  screens, 
grit  chambers,  settling  tanks,  digestion  tanks  or  digestion  compartments 
sprinkling  filters,  secondary  tanks,  sludge  beds,  etc.    These  costs  were 


153 


further  reduced  to  the  cost  per  unit  of  capacity,  either  per  capita,  per 
million  gallons  or  unit  of  organic  load,  so  that  insofar  as  possible  the 
unit  prices  thus  secured  might  be  available  for  use  in  estimates  for 
Chicago  costs. 

The  comparison  of  the  unit  construction  costs  of  these  plants  is 
shown  on  Table  35  hereinbefore  referred  to  under  Imhoff  Tanks. 

On  Table  37  we  have  shown  the  summarized  costs  of  the  sprinkling 
filter  plants  taken  as  a  whole,  without  respect  to  the  variations  in  design 
periods,  rates,  etc.  These  costs  while  more  general  than  those  secured 
from  the  analysis  of  the  several  parts  of  each  plant  nevertheless  are  of 
interest  in  showing  the  average  costs  of  complete  plants  under  widely 
varying  designs.  An  estimate  for  any  particular  set  of  design  conditions 
can  be  prepared  by  applying  the  unit  costs  set  forth  in  Table  38  to  the 
corresponding  units  determined  upon. 

A  study  of  the  operating  costs  of  the  tank-sprinkhng  filter  plants 
was  also  made,  the  results  of  which  are  shown  on  Table  39.  This  table 
shows  contributing  population,, million  gallons  treated  during  the  year, 
the  actual  operating  costs  furnished  us,  these  costs  reduced  to  Chicago 
1925  conditions  and  expressed  in  total,  per  capita,  and  per  million 
gallons. 

All  of  these  plants  are  complete  and  the  costs  of  operation  include 
all  such  items  as  labor  on  coarse  screens  and  grit  chambers,  labor  and 
power  on  fine  screens  at  Baltimore  (the  only  plant  in  this  number  hav- 
ing fine  screens)  sludge  handling,  sludge  drying,  cleaning  of  sprinkler 
nozzles,  operation  of  laboratory,  superintendence,  maintenance  and  re- 
pairs. 

The  detailed  costs  under  each  of  these  subheads  are  not  available 
for  the  several  plants  in  comparable  form  and  are  accordingly  omitted 
herein. 

It  will  be  noted  that  the  weighted  average  cost  of  operating  tank 
sprinkling  filter  plants  was  26.1c  per  capita  or  $8.82  per  million  gallons 
treated,  based  on  Chicago  1925  conditions. 

Activated  Sludge  Plants: 

Three  large  activated  sludge  plants  are  now  in  construction,  namely 
Milwaukee,  Indianapolis  and  the  North  Side  plant  in  Chicago.  The  Mil- 
waukee plant  is  practically  completed,  and  it  is  expected  will  go  into 
operation  this  year.  All  construction  has  either  been  completed  or  is 
under  contract  so  that  the  entire  cost  of  the  work  is  now  ascertained 
within  reasonable  limits. 

Mr.  T.  Chalkeley  Hatton,  Chief  Engineer  of  the  Milwaukee  Sewer- 
age Commission,  has  very  kindly  furnished  us  with  a  most  excellent  de- 


154 


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tailed  analysis  of  the  costs  of  this  plant,  which  is  reproduced  in  summar- 
ized form  on  Table  40.  In  this  table  we  have  adjusted  the  Milwaukee 
costs  for  Chicago  conditions  and  expressed  the  results  in  cost  per  mil- 
lion gallons  and  per  capita  for  each  of  the  several  parts  of  the  plant. 

Mr.  Hatton  has  also  made  a  detailed  study  of  the  estimated  costs  of 
operating  this  plant  based  upon  observations  and  data  collected  during 
the  extended  experimental  work  at  Milwaukee.  These  estimates  of 
operating  cost  are  contained  in  the  Eighth  Annual  Report  of  the  Sewage 
Commission  of  the  City  of  Milwaukee.  We  are  advised  by  Mr.  Hatton 
that  although  these  estimates  were  made  about  three  years  ago,  they  are 
believed  to  represent  conditions  at  the  present  time  except  for  fixed 
charges. 

We  have  also  been  furnished  through  the  courtesy  of  Mr.  Charles 
H.  Hurd,  Consulting  Engineer  of  the  Indianapolis  Commission,  an 
analysis  of  the  construction  cost  of  that  plant,  which  is  reproduced  in 
abstracted  form  on  Table  41. 

In  addition  to  these  two  large  activated  sludge  plants,  both  of 
which  are  substantially  ready  to  start  operation,  there  have  been  two 
activated  sludge  plants  in  Houston,  Texas,  which  have  been  in  operation 
for  over  five  years.  These  plants  have  capacities  of  ten  and  five  million 
gallons  per  day  respectively.  Neither  of  the  Houston  plants  provide  for 
dewatering  of  the  sludge  although  considerable  experimental  work  on 
sludge  dewatering  has  been  carried  on  from  time  to  time. 

The  two  Houston  plants  are  the  only  activated  sludge  plants  in  this 
country  except  the  Des  Plaines  plant  of  the  Chicago  Sanitary  District, 
which  have  had  real  operating-  experience,  although  the  Milwaukee  ex- 
periments were  conducted  on  a  sufficiently  large  scale  to  make  them 
quite  indicative  of  operating  difiiculties  and  costs. 

The  data  relative  to  the  cost  of  construction  of  the  Milwaukee, 
Indianapolis  and  two  Houston  plants  and  of  the  Des  Plaines  River 
plant  of  the  Sanitary  District  of  Chicago,  which  is  substantially  the 
same  size  as  the  small  Houston  plant  built  in  1920,  is  shown  in  Table  42. 

It  will  be  noticed  that  the  weighted  average  cost  of  construction  of 
the  Milwaukee  and  Indianapolis  plants  under  1925  Chicago  conditions 
is  $10.45  per  capita  or  $74,300  per  million  gallons  daily  capacity.  The 
Des  Plaines  plant  has  a  per  capita  cost  of  $30.65  and  a  cost  per  million 
gallons  per  day  of  $306,500. 

These  facts  relative  to  construction  costs  of  all  plants  are  shown 
diagrammatically  on  Figure  26. 

The  cost  of  operating  the  Houston  plants  and  the  estimated  cost  of 
operating  the  Milwaukee  plant,  as  worked  out  in  detail  by  Mr.  Hatton, 
and  the  actual  cost  of  operating  the  Des  Plaines  plant  of  the  Chicago 


159 


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Sanitary  District  for  the  year  1924,  are  shown  in  tabular  form  on 
Table  43  and  diagrammatically  on  Figure  27. 

The  Des  Plaines  plant  of  the  Sanitary  District  of  Chicago  has  an 
operating  cost  approximately  eight  times  the  estimated  cost  of  operating 
the  Milwaukee  plant  expressed  on  the  per  capita  basis,  and  ten  times 
these  figures  when  expressed  in  terms  of  million  gallons  treated. 

The  Des  Plaines  operating  costs  include  some  items  properly 
chargeable  to  experimental  work. 


jnOlAhAP<  )H3 


MOUSTOM 


Mo  Oewa-fe 


MlUWAUKjEE 


PEie>  PUAI 


Ch'iccgo    Soni+crtj  Dis+ric+  \ 


Figure  26. — Cost  of  construction  of  activated  sludge  plants,  based  on  1925 

Chicago  conditions. 

Shaded  areas  are  actual  costs. 

Unshaded  areas  are  corrections  for  Chicago  conditions. 


162 


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Figure  27. — Cost  of  operating  activated  sludge  plants,  based  on 
Chicago  conditions. 

Shaded  areas  are  actual  costs. 

Unshaded  areas  are  corrections  for  Chicago  conditions. 

Pumping  Station  Costs: 

As  due  to  the  level  character  of  the  topography  in  the  Chicago 
district,  practically  all  of  the  sewage  in  Chicago  requires  pumping  be- 
fore treatment,  the  costs  involved  in  the  construction  and  operation  of 
sewage  pumping  stations  becomes  a  large  item. 

In  addition  to  ascertaining  the  facts  relative  to  costs  of  pumping 
stations  and  pumping  station  operations  at  Chicago  we  collected  data 
relative  to  cost  of  construction  and  operation  of  sewage  pumping  sta- 


164 


tions  in  other  cities.  There  are  many  such  stations  scattered  through- 
out the  country,  but  unfortunately  for  our  purposes  most  of  these  sta- 
tions are  smaller  in  size  than  those  required  in  Chicago,  and  most  of  the 
larger  ones  were  built  so  long  ago  as  to  make  the  costs  of  construction 
subject  to  less  accurate _ adjustment  to  the  1925  Chicago  basis  than 
would  be  the  case  if  they  had.  been  built  more  recently. 

We  were,  however,  able  to  secure  sufficient  operating  data  relative 
to  large  sewage  pumping  stations  in  four  cities  to  furnish  a  very  good 
idea  as  to  the  fair  and  reasonable  cost  of  operating  them.  On  Table 
44  we  show  the  cost  of  operating  a  large  number  of  sewage  pumping 
stations  including  the  stations  at  Baltimore,  New  Orleans,  four  stations 
in  Boston  and  the  Albany  sewage  pumping  station,  together  with  several 
stations  operated  by  the  City  of  Chicago  and  the  Chicago  Sanitary 
District. 

Abstracting  from  the  larger  tabulation  only  those  stations  which 
have  an  annual  output  of  about  200,000  million  foot  gallons  per  year 
above  which  there  is  little  reduction  in  the  unit  cost  of  pumping  station 
operation,  we  have  the  following  data: 


Million 

Annual  Cost 

Foot 

per  Million  Foot 

City 

Gallons 

Gallons — Chicago 

Output 

1925  Basis 

591,000 

19.5^* 

New  Orleans  (8  Stations),. 

485,000 

14.1 

Boston  (4  Stations)  

,  ,  1,297,000 

18.0 

Albany   

198,500 

17.4 

160,800 

20.0 

Milwaukee  (Kinnickinnick) 

183,000 

19.6 

  ISM 

Chicago— 

-Sanitary  District. 

39th  St.  (1920)  

432,900 

59.5^ 

Lawrence  Ave.  (1919)  

131,800 

65.3 

Calumet  (1924)    274,000  49.1 

Average    58.0^^ 


The  Chicago  Sanitary  District  pumping  station  operating  costs, 
excluding  power  charge,  average  approximately  three  times  those  of 
similar  stations  elsewhere  including  the  cost  of  power. 

The  operating  costs  are  compared  on  a  basis  of  costs  per  million 
foot  gallons  as  actually  reported  and  as  adjusted  for  the  1925  Chicago 
conditions. 


165 


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The  figures  on  this  table  are  shown  in  diagrammatic  form  on 
Figure  28  and  29. 

Basis  of  Cost  Estimates  in  this  Report: 

The  foregoing  studies  and  cost  analyses  were  used  as  a  basis  for 
estimating  the  reasonable  costs  of  sewers  and  sewage  disposal  works 
required  for  each  of  the  several  flows  considered  as  possibly  available 
for  the  sewage  plant  effluents  of  the  Chicago  Sanitary  District. 

This  adjusted  comparative  method  of  ascertaining  fair  costs  of  con- 
struction and  operation  of  public  works  is  believed  to  furnish  an  excel- 
lent criterion  as  to  the  costs  which  should  practicably  be  secured.  Its  ad- 
vantages include  the  following: 


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Lawc'ENCE /we- Chicago  Sanitary  Dist 


PoweR.  Crene rated 


RICT 


Cent%  Per  Mill-\on  Foot  Gai_L-Ons 

Figure  28. — Operating  costs  of  large  sewage  pumping  stations  (over  200,000 
million  foot  galons  per  year). 

Shaded  areas  are  actual  costs. 

Unshaded  areas  are  corrections  for  Chicago  conditions. 


168 


169 


(a)  Being  based  upon  analyses  of  costs  of  like  work  in  other 
municipalities,  it  automatically  allows  for  the  average  percentage  of  in- 
efficiency found  in  public  enterprises. 

(b)  The  study  embracing  a  large  number  of  cities,  in  this  case 
including  a  study  of  costs  at  Baltimore,  Albany,  Rochester,  Philadelphia, 
Cleveland,  Milwaukee,  Indianapolis,  Houston  and  many  other  important 
cities,  gives  a  representative  average  basis  of  municipal  costs. 

(c)  The  application  of  these  unit  costs  in  this  study  presupposes 
that  the  Sanitary  District  of  Chicago  will  execute  its  construction  pro- 
gram and  its  operations  with  efficiency  and  freedom  from  political  inter- 
ference equal  to  (neither  better  nor  worse)  than  those  found  practicable 
in  other  public  bodies  executing  similar  work. 

(d)  This  method  is  particularly  applicable  to  large  operating 
units  in  which  the  several  operations  are  of  sufficient  magnitude  to  es- 
tablish complete  organizations  such  as  is  the  case  at  all  Chicago  plants. 

This  method  and  the  data  contained  in  Chapter  X  relative  to  sewer 
costs  and  in  this  Chapter  XII  relative  to  sewage  disposal  plant  costs 
have  been  used  as  the  basis  of  estimates  of  costs  of  plants  and  opera- 
tion for  several  flows  studied,  all  as  outlined  in  Chapters  XIII,  XIV, 
and  XV. 


170 


PART  XIII. 

REQUIRED  WORKS  FOR  10,000  CUBIC  FEET 
PER  SECOND  FLOW. 

Basis  of  Cost  Estimates  For  All  Projects: 

With  a  total  flow  in  the  drainage  channel  at  Lockport  of  10,000 
cubic  feet  per  second,  there  will  be  available  during  the  warm  months 
of  July  and  August  approximately  365,000  pounds  of  oxygen  per  day 
in  1935  and  354,000  pounds  per  day  in  1945.  (See  Table  17.)  Of 
this  total  amount  a  relatively  small  part  will  be  required  to  provide  for 
the  effluents  from  the  sewage  disposal  plants  which  are  now  under  con- 
struction or  which  are  included  in  the  tentative  plans  of  the  District 
to  be  constructed  in  the  very  near  future,  all  of  which  it  is  assumed  will 
soon  provide  complete  secondary  treatment. 

The  oxygen  requirements  for  the  effluents  of  these  plants  are  esti- 
mated as  shown  in  Table  45. 

The  amount  of  oxygen  left  for  disposing  of  the  effluents  from  the 
West  and  Southwest  plants  will  be  approximately  330,585  pounds  in 
1935  and  approximately  314,210  pounds  in  1945.  We  have  endeavored 
to  ascertain  the  extent  of  treatment  for  the  West  and  Southwest  Side 
sewage,  which  will  utilize  this  available  oxygen  to  the  fullest  extent  and 
with  the  most  efficiency. 

If  deposits  are  to  be  prevented  in  the  Illinois  River  at  least  tankage 
must  be  installed  at  both  the  West  and  Southwest  plants.  The  installa- 
tion of  tanks  alone  will  reduce  the  B.  O.  D.  of  the  sewage  reaching  the 
two  plants  from  532,500  pounds  to  346,000  pounds  per  day.  As  this 
amount  exceeds  the  330,585  pounds  available  in  the  total  flow  in  the 
channel  of  10,000  C.  F.  S.  some  secondary  treatment  will  be  required 
even  in  1935. 

The  addition  of  sprinkling  filters  to  the  Southwest  plant  will  reduce 
the  B.  O.  D.  of  the  two  plant  effl.uents  to  242,800  pounds  per  day  for 
1935  and  254,900  pounds  per  day  for  1945  conditions.  This  treatment 
will  so  reduce  the  B.  O.  D.  that  the  total  flow  in  the  channel  of  10,000 
C.  F.  S.  would  supply  an  adequate  amount  of  oxygen  up  to  as  late  as 
about  1960. 

Briefly  summarized  a  total  flow  of  10,000  C.  F.  S.  will  provide 
adequately  for  the  dilution  of  treated  sewage  from  the  Sanitary  District 
to  1960  providing: 


171 


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172 


(a)  Activated  sludge  plants  are  in  operation  for  the  North  Side, 
Des  Plaines  and  Stockyards. 

(b)  Tanks  and  Sprinkhng  filters  are  in  operation  for  the  Argo, 
Calumet  and  Southwest  Side. 

(c)  Tanks  are  in  operation  at  the  West  Side. 

Estimated  Cost  of  Works  Required  for  10,000  Cubic  Feet  Per  Second 
Flow: 

We  have  estimated  the  cost  of  the  works  required  to  handle  the 
sewage  of  the  Sanitary  District  of  Chicago,  based  upon  a  total  flow  of 
10,000  cubic  feet  per  second  in  the  Drainage  Canal.  This  estimate  is 
as  follows : 

Construction  Costs 


1935 

1945 

Conditions 

Conditions 

Des  Plaines  Activated  Sludge  

 $  264,700 

$  439,300 

Calumet — Sprinkling  Filters   

  1,564,420 

2,021,700 

North  Side — Activated  Sludge  

  5,600,800 

5,947,300 

Argo — Sprinkling  Filters   

  2,544,200 

2,808,800 

  7,804,800 

8,601,600 

West  Side — Intercepters   

  7,890,600 

7,890,600 

West  Side— Tanks   

  10,120,440 

10,699,700 

S.  W. — Intercepters   

  4,495,700 

4,405,700 

S.  W.  Side— Sprinkling  Filters  

  13,793,500 

16,362,000 

Miscellaneous  Plants   

  3,336,000 

5,336,000 

Total  Estimated  Costs  

 $57,415,240 

$64,692,700 

It  will  be  noted  that  an  expenditure  of  approximately  $57,000,000 
is  required  for  the  1935  sewage  load  even  with  10,000  C.  F.  S.  flow.  If 
the  industries  were  to  pay  one-half  the  cost  of  the  Corn  Products  and 
Stockyards  plants  this  total  would  be  credited  with  approximately 
$5,000,000. 

An  additional  expenditure  of  approximately  $7,000,000  will  be  re- 
quired to  provide  the  additional  capacity  for  1945  conditions.  Even  a 
10,000  cubic  feet  per  second  flow  requires,  as  promptly  as  possible,  com- 
plete treatment ;  that  is,  either  tanks  and  sprinkling  filters  or  activated 
sludge  for  all  of  the  sewage  of  the  Sanitary  District  of  Chicago,  with 
the  exception  of  that  of  the  West  Side  district  which  may  have  tankage 
only  for  the  present. 

Operating  Expenses: 

The  cost  of  operating  the  pumping  and  treatment  plants  outlined 
under  the  10,000  c.  f.  s.  project  is  estimated  as  follows: 


173 


Operating  Expenses 
1935  1945 


Des  Plaines — Activated  Sludge 
North  Side — Activated  Sludge. 


78,500    $  102,240 

882,500  1,042,500 

552,600  611,800 

197,800  244,900 

77,200  86,160 

1,043,300  1,273,200 

1,182,500  1,264,000 

350,000  380,000 


<a)  Stock  Yards — Activated  Sludge 
Calumet — Sprinkling  Filters  . . . 


<a)  Corn  Products — Sprinkling  Filters .  . . 
South  West  Side— Sprinkling  Filters 

West  Side  Tanks  

Miscellaneous  Plants   


Total  Treatment  Oper.  Costs 

(b)  General  Office  Expense  

<b)  Bridge  and  Channel  Expense . . . 


$  4,364,400 
360,000 
253,000 


$  5,004,800 
440,000 
264,000 


Total  Cost  of  Operating  Sanitary  District  $  4,977,400    $  5,708,800 

(Exc'l  fixed  charges) 

♦Credited  with  sale  of  sludge  @  $10. /ton. 

(a)  No  credit  given  for  possibility  of  industries  assuming  part  of  this  cost. 

(b)  Estimated  from  past  study  of  records  of  Sanitary  District. 

We  have  made  no  detailed  analysis  of  the  necessity  for  the  amounts 
shown  as  ''General  Office  Expense"  and  "Bridge  and  Channel  Ex- 
pense". The  amounts  included  in  the  estimated  operating  expenses  of 
the  Sanitary  District  for  each  project  are  the  same  in  each  case" and  are 
based  wholly  upon  a  study  of  expenditures  actually  charged  to  these 
items  in  the  past  by  the  District. 


174 


PART  XIV. 

REQUIRED  WORKS  WITH  4167  CUBIC  FEET 
PER  SECOND  FLOW. 

With  4167  cubic  feet  per  second  total  flow  in  the  Drainage  Canal 
there  would  be  available  during  the  summer  months  of  July  and  August 
approximately  113,200  pounds  per  day  of  oxygen  in  1935  and  103,000 
pounds  per  day  in  1945.  Of  this  total  it  has  been  shown  in  Part  XIII 
that  approximately  33,415  pounds  in  1935  and  39,790  pounds  in  1945 
would  be  required  to  care  for  the  effluent  of  the  Des  Plaines,  Calumet, 
North  Side,  Argo  and  Stockyards  plants.  There  would  therefore  be 
available  from  the  flow  of  4167  c.  f.  s.  approximately  79,785  pounds  of 
oxygen  per  day  in  1935  and  63,210  pounds  in  1945  to  care  for  the 
effluents  from  the  West  and  Southwest  Side  treatment  plants. 

The  total  oxygen  requirement  of  the  sewage  reaching  these  plants 
in  1935  and  1945  is  estimated  as  follows: 

1935  1945 

West  Side  Plant   326,000 #  349,000 # 

Southwest  Side  Plant   206,500  241,000 

Totals    532,500  590,000 

These  totals  are  seven  to  nine  times  the  oxygen  available  from  the 
4167  c.  f.  s.  flow  after  the  other  plant  effluent  requirements  have  been 
satisfied. 

The  type  of  treatment  adopted  therefore  must  be  such  that  it  will 
reduce  the  bio-chemical  oxygen  demand  in  1935  by  approximately 
eighty-five  percent  and  in  1945  by  approximately  eighty-nine  and  one- 
half  percent.  Th  two  most  practicable  methods  of  accompHshing  this 
reduction  are  by  tank-sprinkling  filter  plants  and  by  activated  sludge 
treatment. 

We  have  made  a  comparison  of  the  costs  of  construction  and  the 
costs  of  operation  of  these  two  methods  of  sewage  disposal  as  applied  to 
the  West  Side  and  Southwest  Side  conditions  for  1935  and  1945  respec- 
tively. We  have  also  estimated  the  annual  costs,  which  are  made  up  of 
interest  which  we  have  taken  at  four  percent,  depreciation  which  we 
have  taken  at  two  percent  on  sprinkling  filter  plants  and  four  percent 
on  activated  sludge,  and  operating  costs.  The  higher  depreciation  al- 
lowance for  activated  sludge  plants  is  adopted  because  of  the  process 


175 


requiring  more  mechanical  equipment  of  relatively  short  life  and  which 
due  to  the  present  experimental  nature  of  the  process  suffers  higher  ob- 
solescence than  sprinkling  filters  which  have  been  in  use  a  generation 
or  more. 

In  both  the  cost  of  construction  and  the  cost  of  operating  activated 
sludge  plants  we  have  based  our  estimates  upon  two  sets  of  conditions : 

First.  Complete  plants,  including  equipment  for  sludge  pressing, 
drying  and  storage  and  including  in  the  operating  expenses  a  credit  for 
the  sale  of  sludge  and 

Second.  Based  upon  no  drying  or  storage  of  sludge  but  instead 
upon  pumping  the  sludge  to  abandoned  quarries  and  vacant  land  along 
the  drainage  canal. 

Table  46  shows  the  comparative  first  and  annual  costs  of  construc- 
tion under  each  of  these  three  alternatives.  It  will  be  noticed  that  so 
far  as  first  cost  is  concerned  approximately  $10,000,000  is  saved  in  in- 
vestment in  the  construction  of  an  activated  sludge  plant  with  no  sludge 
pressing  or  drying  equipment  as  compared  to  either  of  the  other  plants. 
The  annual  cost  of  operation  of  a  disposal  plant  of  this  type,  however, 
is  approximately  $300,000  greater  than  that  of  the  tanks  and  sprinkling 
filters  in  1935  and  approximately  $500,000  per  year  greater  in  1945. 

The  cost  of  activated  sludge  treatment,  including  complete  sludge 
drying,  and  crediting  the  operating  cost  with  a  revenue  from  sludge 
sales  equivalent  to  $10.00  per  ton  of  sludge,  is  about  fifteen  percent  to 
twenty  percent  higher  than  that  of  either  the  sprinkling  filter  or  the 
activated  sludge  plan  with  lagooning  of  sludge. 

The  sludge  produced  by  the  activated  sludge  method  is  about 
ninety-eight  to  ninety-nine  percent  moisture  as  compared  to  eighty-five 
to  ninety  percent  moisture  for  Imhoff  tank  sludge.  In  volume,  there- 
fore, it  is  from  seven  to  ten  times  as  great  as  tank  sludge  from  sewage 
of  the  same  solid  content.  The  sludge  disposal  problem  with  the  acti- 
vated sludge  process  is  a  difficult  one.  Sludge  drying  is  possible  but 
the  practicability  of  drying  it  at  a  cost  less  than  the  am.ount  which  can 
be  realized  from  its  sale  as  fertilizer  has  not  as  yet  been  fully  demon- 
strated. It  is  possible  to  lagoon  this  sludge  and  for  this  purpose  the 
Sanitary  District  of  Chicago  has  available  a  large  amount  of  land  and 
abandoned  quarry  capacity. 

In  order  to  secure  some  idea  as  to  the  practicability  of  lagooning  or 
disposing  of  large  quantities  of  wet  sludge  in  the  abandoned  quarries, 
we  have  given  this  phase  of  the  matter  some  little  attention.  We  have 
been  furnished  by  the  Sanitary  District  with  a  study  which  has  been 
made  by  the  district  of  the  abandoned  quarries  along  the  main  drainage 
channel.  Ten  abandoned  quarries  with  a  total  storage  capacity  of  nearly 


176 


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177 


5,000,000  cubic  yards  were  located  between  Summit  and  Lockport. 
Nearly  half  of  the  total  capacity  is  located  immediately  adjacent  to 
Summit. 

If  is  the  Sanitary  District's  plan  to  utilize  these  quarries  for  dis- 
posal of  the  sludge  from  the  North  side  activated  sludge  plant,  which  is 
now  under  construction,  and  from  which  the  sludge  will  be  conducted 
to  the  quarries  through  a  cast  iron  force  main. 

The  sludge  as  pumped  will  contain  approximately  two  percent  of 
sludge  materials  and  ninety-eight  percent  of  moisture.  It  will  amount 
to  approximately  1,100,000  gallons  per  day  at  the  present  time,  increas- 
ing to  approximately  1,790,000  gallons  per  day  by  1945.  After  this  ex- 
tremely wet  sludge  is  pumped  into  the  quarries  which  have  depths  as 
great  as  approximately  100  feet,  and  as  the  quarries  fill,  the  sludge  will 
be  to  a  certain  extent  dewatered  due  to  the  hydraulic  pressure  exerted. 

If  there  was  no  dewatering  effect  the  total  capacity  of  all  the  quar- 
ries would  be  sufficient  for  the  sludge  from  the  North  Side  plant  alone 
for  only  about  two  years  and  four  months.  If  the  sludge  dewaters  itself 
to  ninety  percent  moisture  as  an  average,  these  quarries  would  be  suffi- 
cient for  the  North  Side  sludge  for  a  period  of  twelve  years.  If  the 
sludge  should  be  dewatered  due  to  its  depth  and  pressure  to  eighty  per- 
cent moisture  these  quarries  would  be  sufficient  for  the  North  Side  plant 
sludge  for  about  twenty-four  years. 

In  addition  to  the  abandoned  quarries,  the  Sanitary  District  owns  a 
strip  of  land  in  many  places  nearly  a  mile  in  width  and  extending  over 
most  of  the  reach  from  Summit  to  Lockport,  a  distance  of  some  fifteen 
miles.  The  total  area  between  summit  and  Lockport  is  approximately 
3,200  acres.  Most  of  this  land  is  of  little  value  from  the  agricultural 
standpoint  and  is  lying  idle  at  the  present  time. 

If  the  West  and  Southwest  plants  were  also  to  be  provided  with 
activated  sludge  type  treatm.ent,  and  the  sludge  lagooned  in  the  quarries 
and  on  this  vacant  ground,  the  amount  of  sludge  to  be  handled  would  be 
greatly  increased  and  its  disposal  would  become  a  much  more  difficult 
problem.  The  quantity  of  wet  sludge  to  be  taken  care  of  from  the  North 
Side,  the  West  and  Southwest  Side  plants  combined  would  be  over 
four  times  that  to  be  handled  from  the  North  Side  alone.  All  the  quar- 
ries covered  by  the  Sanitary  District  survey  would  be  filled  in  less  than 
seven  months  by  the  sludge  pumped  from  these  three  plants  if  it  is 
assumed  that  there  would  be  no  reduction  in  the  moisture  content  below 
the  ninety-eight  percent  at  which  it  reached  the  quarries. 

If  the  moisture  content  were  reduced  to  ninety  percent  all  of  the 
quarries  would  last  for  only  two  years  and  ten  months,  and  if  the  sludge 
moisture  were  reduced  to  eighty  percent  all  of  these  quarries  would  last 
only  five  years  and  seven  months. 


178 


The  question  of  disposing  of  this  vast  amount  of  wet  sludge  is 
therefore  a  real  problem.  It  is  so  great  in  quantity  that  an  area  of 
approximately  nine  square  miles,  that  is  one  mile  in  width  and  nine 
miles  in  length  extending  along  the  drainage  canal,  would  be  covered 
with  wet  sludge  to  a  depth  of  one  foot  each  year.  The  land  owned  by 
the  Sanitary  District  would  have  to  take  a  dosage  of  nearly  twenty 
inches  per  year.  There  would  of  course  be  some  very  material  shrink- 
age in  the  drying  out  of  this  sludge.  However,  there  is  no  data  available 
from  which  it  is  possible  to  determine  with  any  degree  of  certainty  what 
the  conditions  of  sludge  drying  under  these  conditions  of  lagooning 
would  be. 

It  might  be  found  that  by  skillful  utilization  of  the  land  and  quar- 
ries for  lagooning,  the  sludge  from  all  three  plants  could  be  disposed  of 
without  the  installation  of  sludge  pressing  and  drying  equipment  for  a 
considerable  period.    The  uncertainties  are,  however,  very  great. 

In  view  of  the  fact  that  the  activated  sludge  treatment  will  reduce 
the  oxygen  demand  of  the  effluent  below  that  of  sprinkling  filter  plants 
(ninety-two  percent  compared  to  eighty-eight  percent  B.  O.  D.  re- 
duction) and  thus  extend  the  period  for  which  expenditures  now  to  be 
made  at  the  West  and  Southwest  plants  will  be  adequate  and  in  view 
of  the  further  fact  that  the  costs  of  constructing  the  two  types  of  plants 
are  substantially  the  same  including  complete  sludge  handling  equipmnt 
in  the  activated  sludge  treatment,  it  is  believed  that  the  procedure  for 
handling  the  sewage  of  the  West  and  Southwest  Side  districts  with  a 
total  flow  restricted  to  4167  C.  F.  S.  is  through  activated  sludge  which 
will  adequately  treat  the  sewage  with  a  flow  in  the  channel  of  4167 
C.  F.  S.  as  late  as  1952. 

While  it  might  be  practicable  to  lagoon  the  sludge  at  least  for  a 
time  it  is  believed  that  complete  sludge  handling  equipment  should  be 
provided  for  in  this  project  and  this  has  accordingly  been  done. 

We  have  estimated  the  cost  of  the  disposal  works  required  for  a 
4167  cubic  feet  per  second  flow  as  follows : 

Estimated  Cost  of  Works  Required  for  4167  C.F.S.  Diversion. 


Des  Plaines  Activated  Sludge  Plant 
Calumet — Sprinkling  Filters   


1935 
$  264,700 


439,300 
2,021,700 
5,947,300 
2,808,800 
8,601,600 

22,544,600 
7,890,600 

16,496,700 


1045 


(a)  S.  W.  Side — Activated  Sludge 


(a)  West  Side — Activated  Sludge 


North  Side — Activated  Sludge  Plant 
*Corn  Products — Sprinkling  Filters. 
*  Stockyards — Activated  Sludge  Plant 


West  Side — Intercepters 


1,564,420 
5,600,800 
2,544,200 
7,804,800 

21,287,900 
7,890,600 

14,424,400 


179 


S.  W.  Side— Intercepters   4,495,700  4,495,700 

Miscellaneous  Plants    3,336,000  5,336,000 

Total  Estimated  Costs  $69,213,520  $76,583,300 

•  San.  Dist.  has  started  suit  to  require  industries  to  bear  part  of  this  cost, 
(a)    Sludge  drying  included. 

It  will  be  noted  that  a  total  expenditure  of  over  $69,000,000  will  be 
required  by  1935  for  intercepting  sewers  and  sewage  disposal  for  the 
complete  treatment  of  the  sewage  of  the  West  and  Southwest  side 
plants  to  the  degree  which  will  enable  the  effluent  from  these  plants  to- 
gether with  the  effluent  of  the  other  plants  within  the  Sanitary  District  of 
Chicago  to  be  adequately  provided  with  the  necessary  oxygen  by  a  flow 
of  4167  cubic  feet  per  second  in  the  Drainage  Canal.  By  1945  an  addi- 
tional $7,000,000  of  investment  will  be  required  to  take  care  of  the 
increased  demand  due  to  population  and  industrial  growth.  By  1952 
with  a  flow  of  4,167  C.  F.  S.  additional  refinement  to  still  further  reduce 
the  B.  O.  D.  will  probably  become  necessary. 

Both  of  the  above  figures  include  the  entire  cost  of  disposal  w^orks 
for  the  stockyards  and  Corn  Products  wastes.  If  half  of  the  cost  of 
these  works  is  properly  chargeable  to  the  industries  creating  these 
wastes,  approximately  $5,000,000  should  be  deducted  from  the  figures 
for  both  the  1935  and  1945  debts. 

The  cost  of  operating  the  puniping  and  treatment  plants  outlined 
under  the  4,167  C.  F.  S.  project  is  estimated  as  follows: 


1935  1945 

Des  Plaines  Activated  Sludge  $      78,500    $  102,240 

Calumet— Sprinkling  Filters                                       197,800  244,900 

North  Side— Activated  Sludge                                  882,500  1,042,500 

(a)  Corn  Products— Sprinkling  Filters  ,                  77,200  86,160 

(a)  Stockyards— Activated  Sludge                                    552,600  611,800 

♦West  Side  Activated  Sludge                                  1,776,500  1,941,000 

*S.  W.  Side  Activated  Sludge                                   1,248,000  1,409,000 

Miscellaneous  Plants                                                 350,000  380,000 


Totals   $  5,163,100    $  5,817,600 

General  Office  Expense   360,000  440,000 

Bridge  and  Channel  Expenses   253,000  264,000 


Total  Fair  Cost  of  Operating  District   5,776,100  6,521,600 


♦Credited  with  the  sale  of  sludge  @  $10/ton. 

(a)    No  credit  given  for  industries  possibly  assuming  part  of  this  cost. 


180 


PART  XV. 

REQUIRED  WORKS  WITH  MISCELLANEOUS  FLOWS. 

In  addition  to  the  channel  flows  of  10,000  c.  f.  s.  and  4,167  c.  f.  s. 

discussed  in  detail  in  Parts  XITI  and  XIV,  respectively,  we  have  made 
studies  of  the  requirements  and  the  costs  of  sewage  disposal  with  flows 
of  2,000,  6,000,  7,500,  and  8,500  c.  f.  s. 

Required  Works  with  2,000  C.  F.  S.  Flow: 

With  2,000  c.  f.  s.  flow  there  would  be  available  during  the  months 
of  July  and  August  approximately  20,200  pounds  of  oxygen  per  day  in 
1935,  and  10,000  pounds  per  day  in  1945.  As  hereinbefore  shown,  the 
oxygen  requirements  for  the  effluent  of  the  Des  Plaines,  Calumet, 
North  Side,  Corn  Products  and  Stockyards  plants  are  33,415  pounds  of 
oxygen  in  1935  and  39,790  in  1945. 

Inasmuch  as  the  effluents  from  the  above  plants  require  more  oxy- 
gent  even  at  the  present  time  than  is  available  in  the  2,000  c.  f.  s.  total 
flow  in  the  channel,  it  is  obvious  that  there  is  no  practicable  means  of 
meeting  the  requirements  of  the  pollution  standard  hereinbefore  out- 
lined with  so  small  a  flow  in  the  channel. 

Many  cities  are  so  located  that  standards  less  adequate  are  neces- 
sarily adopted ;  however,  a  pollution  standard  which  provides  for  a 
thriving  fish  life  in  Illinois  River  cannot  practicably  be  complied  with 
when  the  total  flow  in  the  Drainage  Canal  is  as  low  as  2,000  c.  f.  s. 

Required  Works  with  6,000  C.  F.  S.  Flow: 

With  a  total  flow  of  6,000  c.  f.  s.  in  the  Drainage  Canal,  the  avail- 
able oxygen  during  July  and  August  would  be  approximately  192,000 
pounds  per  day  in  1935  and  182,000  pounds  in  1945.  Of  this  amount 
33,415  pounds  in  1935  and  39,790  pounds  in  1945  wiU  be  required  for 
the  effluents  of  the  Des  Plaines,  Calumet,  North  Side,  Corn  Products 
and  Stockyards  plants,  leaving  158,585  pounds  in  1935  and  142,210 
pounds  in  1945  for  the  West  and  Southwest  plant  effluents.  The  fol- 
lowing table  shows  the  requirements  of  these  two  plant  sewages  with 
varying  types  of  treatment : 


181 


Type  of  Treatment  B.O.D.  of  Effluents  from 

West                          Southwest  Both  Plants 

Side                               Side  1935  1945 

Raw  Sewage  Kaw  Sewage    532,500  lbs.       589,000  lbs. 

Tanks  Tanks    346,000  lbs.      383,000  lbs. 

Tanks  Sprinkling  Filters    236,800  lbs.       254,900  lbs. 

Sprinkling  Filters. .  .Sprinkling  Filters    63,900  lbs.        70,600  lbs. 

Sprinkling  Filters. .  .Tanks    173,100  lbs.      198,700  lbs. 

Activated  Sludge. .. .Activated  Sludge    42,600  lbs.       47,100  lbs. 

Sand  Filters  Sand  Filters    0  lbs.              0  lbs. 

From  the  above  table  it  is  apparent  that  nothing  less  than  sprink- 
ling filters  for  both  plants  will  accompHsh  the  results.  The  flow  of 
6,000  c.  f.  s.  accordingly  requires  the  construction  of  tanks  and  sprink- 
ling filters  at  both  the  West  and  Southwest  plants. 

We  have  estimated  the  cost  of  the  disposal  works  required  for  a 
6,000  cubic  feet  per  second  flow  as  follows : 


Estimated  Cost  of  Works  Required  for  6,000  C.F.S.  Flow. 


1935 

1945 

Des  Plaines  Activated  Sludge  Plant  

 $  264,700 

$  439,300 

  1,564,420 

2,021,700 

North  Side — Activated  Sludge  Plant  

  5,6-00,800 

5,947,300 

  2,544,200 

2,808,800 

  7,804,800 

8,601,600 

  21,431,700 

22,837,100 

West  Side — Intercepters   

  7,890,600 

7,890,600 

S.  W.  Side— Sprinkling  Filters  

  13,793,500 

16,362,000 

  4,495,700 

4,495,700 

Miscellaneous  Plants   

  3,338,000 

5,336,000 

Total  Estimated  Costs  $  68,726,620    $  76,740,100 

*San.  Dist.  has  started  suit  to  require  industries  to  bear  part  of  this  cost. 

Both  of  the  above  figures  include  the  entire  cost  of  disposal  works 
for  the  stockyards  and  Corn  Products  wastes.  If  half  of  the  cost  of 
these  works  is  properly  chargeable  to  the  industries  creating  these 
wastes,  approximately  $5,000,000  should  be  deducted  from  the  figures 
for  both  1935  and  1945. 

The  cost  of  operating  the  pumping  and  treatment  plants  outlined 
under  the  6,000  c.  f .  s.  project  is  estimated  as  follows : 


Plant 

1935 

1945 

 $  78,500 

$  102,240 

Calumet — Sprinkling  Filters   

  197,800 

244,900 

  882,500 

1,042,500 

(a)  Corn  Products — Sprinkling  Filters  

  77,200 

86,160 

*  (a)  Stockyards — Activated  Sludge   

552,600 

611,800 

182 


West  Side— Sprinkling  Filters.   1,637,500  1,749,200 

S.  W.  Side— Sprinkling  Filters   1,043,300  1,273,200 

Miscellaneous  Plants    350,000  380,000 

Totals   $  4,819,400  $  5,490,000 

General  Office  Expense  $  360,000  $  440,000 

Bridge  and  Channel  Expense   253,000  264,000 

Total  Fair  Cost  of  Operating  District  $  5,432,400  $  6,194,000 


*Credited  with  the  sale  of  sludge  @  $10/ton. 

(a)    No  credit  given  for  industries  possibly  assuming  part  of  this  cost. 

Required  Works  With  7,500  Cubic  Feet  Per  Second: 

With  a  flow  in  the  channel  of  7,500  c.  f.  s.  there  will  be  available 
257,000  pounds  of  oxygen  per  day  during  the  months  of  July  and 
August  in  1935  and  246,000  pounds  in  1945.  It  would  be  possible  to 
keep  the  total  oxygen  demand  of  the  sewage  and  industrial  wastes  of 
the  entire  district  below  this  amount  of  available  oxygen  by  having  con- 
structed activated  sludge  plants  at  Des  Plaines,  the  North  Side  and 
Stockyards,  and  sprinkling  filter  plants  at  Calumet,  the  Corn  Products 
Plant  and  at  the  West  Side  Plant,  with  tanks  at  the  Southwest  Side 
Plant.  Soon  after  1945  a  part  of  the  sprinkling  filters  for  the  South- 
west plant  would  have  to  be  constructed,  as  by  that  time  the  oxygen 
demand  of  the  effluents  would  exceed  the  available  oxygen. 

It  has,  therefore,  been  assumed  that  for  7,500  c.  f.  s.  flow  the  West 
plant  would  be  a  complete  sprinkling  filter  plant  constructed  at  once, 
and  that  the  Southwest  plant  would  have  tanks  only.  Under  this  pro- 
gram the  oxygen  provided  by  the  7,500  c.  f.  s.  flow  would  be  suflicrent 
to  care  for  the  effluent  from  all  plants  as  late  as  1947. 

The  estimated  cost  of  construction  under  this  program  is  as 
follows : 


1935 

1945 

Des  Plaines  Activated  Sludge  

 %  264,700 

$  439,300 

Calumet  Sprinkling  Filters  

  1,564,420 

2,021,700 

North  Side  Activated  Sludge  

  5,600,800 

5,947,300 

Corn  Products  Sprinkling  Filters  

  2,544,200 

2,808,800 

  7,804,800 

8,601,600 

  21,431,700 

22,837,100 

West  Side  Intercepter  

  7,890,600 

7,890,600 

  6,545,000 

7,548,000 

  4,495,700 

4,495,700 

  3,336,000 

5,336,000 

Total   

 $61,477,920 

$67,926,100 

183 


The  cost  of  operating  the  pumping  and  treatment  plants  outlined 
under  the  7,500  c.  f.  s.  project  is  estimated  as  follows: 


1  Q*? 

 $  78,500 

$  102,240 

Calumet  Sprinkling  Filters  

  197,800 

244,000 

882,500 

1,042,500 

77,200 

86,160 

552,600 

611,800 

West  Side  Sprinkling  Filters  

1,637,500 

1,749,200 

Southwest  Side  Settling  Tanks  only  

754,300 

920,200 

350,000 

380,000 

Total   

$  4,530,400 

$  5,137,000 

General  Office  Expenses  

360,000 

440,000 

Bridge  and  Channel  Expenses   

253,000 

264,000 

Total  Fair  Cost  of  Operating  Sanitary  District.  .$  5,143,400    $  5,841,000 

*  Credited  with  the  sale  of  sludge  @  $10.00  per  ton. 
(a)    No  credit  given  for  industries  assuming  part  of  this  cost. 

Required  Works  with  8,500  Cubic  Feet  Per  Seeond  Flozc: 

With  8,500  cubic  feet  per  second  flow,  the  oxygen  available  would 
amount  to  approximately  300,000  pounds  per  day  in  1935,  and  289,000 
pounds  in  1945.  A  study  of  the  utilization  of  this  amount  of  oxygen 
shows  that  it  would  require  no  more  construction  up  to  as  late  as  1945, 
than  would  be  required  for  10,000  cubic  feet  per  second,  or,  in  other 
words,  that  the  difiference  in  the  oxygen  supply  between  8,500  and 
10,000  second  feet  flow  is  insufficient  to  permit  of  the  adoption  of  a 
less  efficient  type  of  treatment  at  any  one  of  the  plants  yet  to  be  con- 
structed. 

The  dilution  afforded  by  8,500  c.  f.  s.  is  obviously  less  than  that 
afforded  by  10,000  c.  f.  s.  but  the  dift'erence  is  not  sufficient  to  permit 
the  adoption  of  a  less  degree  of  purification  at  either  the  West  or  South- 
west plant  considered  as  a  whole.  The  providing  of  secondary  treat- 
ment for  a  part  only  of  either  plant  is  considered  an  unwarranted  refine- 
ment in  this  comparison,  it  being  considered  preferable  to  express  the 
advantage  of  10,000  c.  f.  s.  over  8,500  by  stating  that  the  expenditures 
with  10,000  c.  f.  s,  will  be  adequate  until  1960  while  further  expendi- 
tures will  be  required  by  1945  if  the  flow  is  8,500  c.  f.  s. 

.  The  works  required,  therefore,  for  8,500  cubic  feet  per  second 
diversion  are  considered  the  same  as  those  required  for  the  10,000  cubic 
feet  per  second  diversion,  which  was  outlined  quite  fully  in  Part  XIIL 
The  construction  costs  and  the  annual  cost  of  operation  are  the  same  as 
therein  set  forth. 


184 


An  expenditure  of  $57,415,240  would  be  required  for  construction 
up  to  1935.  The  annual  cost  of  operating  the  District  in  1935  (exclu- 
sive of  fixed  charges)  is  estimated  as  $4,977,400. 

By  1945  the  total  construction  expenditure  will  have  reached 
$64,692,700  and  the  cost  of  operating  the  District  increased  to  $5,708,- 
800  (exclusive  of  fixed  charges). 


185 


PART  XVI. 

REVIEW  OF  EXPENDITURES  UNDER  VARIOUS  FLOWS 

In  Parts  XITI,  XIV  and  XV  the  utilization  of  the  oxygen  provided 
by  flows  of  2,000,  4,167,  6,000,  7,500,  8,500,  and  10,000  cubic  feet  per 
second  has  been  discussed  and  estimates  of  the  cost  of  constructing  and 
operating  the  various  disposal  works  best  adapted  to  the  utilization  of 
this  oxygen  has  been  outlined.  The  figures  of  construction  and  annual 
cost  of  operation  for  1935  and  1945  which  cover  conditions  for  each  of 
these  flows,  have  been  summarized  as  shown  in  Table  1. 

A  study  of  this  table  shows  that  so  far  as  1935  is  concerned  an 
expenditure  of  $57,415,240  will  be  required,  even  with  10,000  cubic 
feet  per  second,  and  that  this  expenditure  would  only  be  increased 
$11,000,000  or  approximately  twenty  percent  in  order  to  meet  the  more 
exacting  requirements  of  a  flow  as  low  as  4,167  cubic  feet  per  second. 

The  cost  of  operation  in  1935  (exclusive  of  fixed  charges)  of  the 
works  required  with  10,000  cubic  feet  per  second  flow  would  be  $4,364,- 
000  per  year,  and  $5,163,100  or  about  eighteen  percent  higher,  with  the 
flow  of  but  4,167  cubic  feet  per  second. 

In  other  words,  the  difference  between  the  completeness  of  the 
treatment  processes  required  under  the  10,000  and  4,167  cubic  feet  per 
second  projects  under  the  1935  conditions  represents  a  difference  in 
expenditures  for  plant  construction  of  approximately  $11,000,000 
(20%)  and  a  difference  in  operating  costs  of  approximately  $800,000 
(18%)  per  year. 

As  applied  to  the  1945  conditions,  the  10,000  cubic  feet  per  second 
project  will  require  a  total  expenditure  of  approximately  $64,692,700 
as  compared  to  approximately  $76,583,300  if  the  flow  were  but  4,167 
cubic  feet  per  second,  the  latter  construction  cost  being  nineteen  per- 
cent higher  than  the  former.  The  cost  of  operation  for  1945  conditions 
will  be  approximately  $5,004,800  with  10,000  cubic  feet  per  second  and 
approximately  $5,817,600  with  4,167  cubic  feet  per  second  flow,  the  lat- 
ter being  sixteen  percent  higher  than  the  former. 

The  construction  outlined  under  the  10,000  cubic  feet  per  second 
flow  will,  however,  be  adequate  to  meet  the  conditions  to  approximately 
1960,  while  the  construction  outlined  under  the  4,167  cubic  feet  per  sec- 
ond diversion  will  become  inadequate  about  1950.   Additional  expendi- 


186 


tures  will  be  required  at  an  earlier  date  under  the  4,167  cubic  feet  per 
second  plan  than  under  the  one  outlined  for  10,000  c.  f.  s. 

We  have  prepared  a  diagram  showing  the  adequacy  of  the  various 
flows  with  varying  degrees  of  sewage  treatment.  This  diagram  shows 
the  length  of  time  for  which  various  projects  will  be  adequate  and  when 
additional  treatment  or  greater  quantities  of  dilution  water  are  neces- 
sary. 


4oo,ooo 


n3o 


jc|4o  ic|43 


Figure  30. — Adequacy  of  various  dilutions  with  various  degrees  of  sewage  ^ 
disposal,  based  on  (1)  activiated  sludge  at  Northside  &  Stock 
Yards,  and  (2)  tanks  and  filters  at  Argo  and  Calumet. 

Reduction  in  B.  0.  D. 

Basis:    Imhoff   tanks   35% 

Imhoff  tanks  and  sprinkling  filters  88% 

Activated  sludge,  domestic  sewage  92% 

Stock  yards  and  corn  products  95% 

All  of  these  costs  include  the  full  cost  of  the  Stockyards  and  Argo 
plants,  for  the  collection  of  a  part  of  which  the  Sanitary  District  of 


187 


Chicago  has  instituted  suits  against  the  Packers  and  the  Corn  Products 
Company,  respectively. 

These  estimated  costs  are  also  based  upon  the  construction  of  a  sep- 
arate plant  to  handle  the  Stockyards  wastes.  It  would  seem  that  there 
might  be  very  substantial  savings  effected  by  the  combining  of  this 
waste  with  the  domestic  sewage  of  the  West  and  Southwest  Side  plants, 
which  would  result  in  diluting  this  strong  waste  approximately  fifteen 
parts  of  domestic  sewage  to  each  part  of  Stockyards  waste,  and  enable 
it  to  be  readily  handled  by  the  secondary  treatment  to  be  added  at  the 
South  and  Southwest  Side  sites.  This  possibility  is  so  important  and 
involves  such  large  expenditures  that  we  have  given  it  somewhat  de- 
tailed consideration. 

Separate  Activated  Sludge  Plant  for  Treatment  of  Stockyards  Wastes 
z's.  Sprinkling  Filter  Treatment  of  Combination  of  Stocky a/rds  with 
West  and  Southwest  Plant  Sewages: 

The  possibility  of  combining  the  industrial  waste  from  the  stock- 
yards with  the  immense  amount  of  sewage  to  be  treated  at  the  West  and 
Southwest  Side  plants,  which  will  be  so  located  as  to  be  substantially 
one  plant,  is  suggested  by  the  fact  that  the  Southwest  Side  intercepting 
sewer  runs  practically  by  the  site  of  the  proposed  Stockyards  disposal 
plant.  The  combining  of  all  of  these  sewages  and  thus  obviating  the 
costly  construction  and  operation  of  an  activated  sludge  plant  is  further 
suggested  by  the  necessity  of  building  either  the  West  or  Southwest 
Side  plant  complete  at  an  early  date,  under  any  flows  in  the  channel 
herein  considered ;  and  both  plants  for  any  flow  under  7,500  c.  f.  s. 
whereas  it  has  apparently  been  the  thought  of  the  Sanitary  District  that 
the  construction  of  these  plants  to  give  any  greater  degree  of  purifica- 
tion than  tankage  was  a  matter  of  the  far  distant  future. 

The  Stockyards  wastes,  while  very  strong  and  having  a  high  oxy- 
gen demand,  are  small  in  volume,  amounting  at  the  present  time  to  only 
32,000,000  gallons  per  day,  increasing  to  40,000,000  gallons  per  day 
average  in  1940.  The  necessary  sewer  capacity  to  transport  this  small 
additional  flow  from  the  Stockyards  to  the  West  and  Southwest  Side 
plants  is  not  a  material  item. 

We  have  estimated  the  effect  of  adding  this  amount  of  flow  to  the 
Southwest  Side  intercepter,  and  find  that  it  will  increase  the  cost  of  this 
sewer  only  $472,000. 

Eifect  of  Stockyards  Wastes  upon  Sewage  at  West  and  Southwest  Side 
Plants: 

The  total  quantity  of  sewage  to  be  handled  by  the  West  and  South- 
west Side  plants  under  complete  metering  amounts  to  468,000,000 


188 


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gallons  per  day  in  1935  and  528,000,000  gallons  per  day  in  1945,  as  com- 
pared to  the  volume  of  the  Stockyards  wastes  of  32,000,000  and  40,- 
000,000  gallons  per  day  respectively,  at  these  two  periods.  The  Stock- 
yards waste,  however,  has  a  very  high  oxygen  demand,  and  we  have 
made  some  study  of  the  practicability  of  handling  the  combined  domes- 
tic sewage  and  stockyards  wastes  of  these  amounts  with  sprinkling 
filter  treatment. 

Table  47  shows  the  facts  relative  to  the  sewage  flow  and 
the  strength  of  the  sewage  to  be  handled  by  the  West  and 
Southwest  Side  plants  with  and  without  the  addition  of  the  Stockyards 
wastes.  It  will  be  noted  that  even  with  the  Stockyards  waste  added  to 
the  domestic  sewages  of  the  West  and  Southwest  Side  district,  the  com- 
bined oxygen  demand  in  1946  will  be  but  170,  as  compared  to  an  aver- 
age for  Columbus  of  190  parts  per  million. 

We  have  further  made  investigations  as  to  the  relative  amount  of 
packinghouse  wastes  in  Chicago,  as  compared  to  other  cities,  the  results 
of  which  are  summarized  in  Table  48. 

It  will  be  noticed  that  the  total  pounds  of  live  stock  slaughtered  in 
Chicago  per  person  tributary  to  the  West  and  Southwest  Side  plants  is 
somewhat  less  than  that  in  Indianapolis,  and  only  slightly  above  that  at 

TABLE  48. 

IMPORTANCE  OF  PACKING  HOUSE  WASTES  IN  VARIOUS  CITIES. 


Total  Pounds 

Pounds 

of  Animals 

Slaughtered 

City. 

Year. 

Slaughtered 

Per  Capita. 

1922 

3,896,017,318 

1442  d 

1923 

4,326,242,144 

1601  d 

1924 

4,186,373,884 

1549  d 

(b)  Milwaukee   

1922 

440,000,000* 

963 

1923 

497,000,000* 

1069 

1924 

461,200,000 

1008 

1922 

353,000,000 

482 

1923 

395,000,000 

538 

1924 

397,000,000 

542 

  1924 

71,000,000 

1385 

(c)  IndlanapoHs   

  1922 

517,000,000 

1645 

1923 

555,000,000 

1768 

1924 

526,000,000 

1673 

.     ,  1922 

38,000,000 

493 

1923 

38,800,000 

510 

1924 

43,100,000 

566 

(a)  Head  and  weights  of  each  class  available. 

(b)  Head  and  part  of  weights  available. 

(c)  Head  available,  weights  estimated  from  data  available  for  all  markets  or  adjacent 
markets. 

(d)  Based  on  population  tributary  to  West  and  S.  W.  side  plants,  including  300,000  tran- 
sient population. 

*  Estimated  on  basis  of  1924. 


190 


Madison,  Wis.  At  the  latter  place  it  is  being  handled  mixed  with 
domestic  sewage  at  a  plant  which  has  a  loading  of  3,400  people  per 
acre  foot  of  stone  beds  and  the  stone  beds  are  being  dosed  at  a  rate  of 
approximately  two  and  one-half  million  gallons  per  acre  per  day,  and 
producing  an  excellent  effluent. 

At  Indianapolis  where  the  pounds  kill  per  capita  is  greater  than  at 
Chicago,  the  packing  wastes  are  to  be  mixed  with  the  domestic  sewage 
and  the  mixture  treated  at  the  sewage  disposal  plant  by  the  activated 
sludge  method  and  the  use  of  but  one  cubic  foot  of  air  per  gallon  of 
sewage. 

At  Milwaukee  a  packing  house  waste  two-thirds  as  great  propor- 
tionately as  that  at  Chicago  is  to  be  treated  with  other  trade  wastes 
mixed  with  the  domestic  sewage,  all  at  one  disposal  plant. 

The  Baltimore  sprinkling  filter  plant  handling  a  concentrated  do- 
mestic sewage  with  a  packing  house  waste  one-third  as  great  propor- 
tionately as  that  at  Chicago  has  been  operating  satisfactorily  for  years 
at  a  dosage  rate  of  3,500  people  per  acre. 

It  is  believed  that  it  should  be  possible  to  dose  the  filters  of  the 
South  and  Southwest  Side  plants  with  domestic  sewage  computed  at  a 
rate  of  160  gallons  per  capita  per  day  to  which  has  been  added  about 
eight  percent  by  volume  of  packing  house  wastes,  and  maintain  a  rate 


SAVINGS  EFFECTED  BY  COMBINING  STOCKYARDS  WITH  WEST  AND 


SOUTHWEST  PLANTS  (1935  CONDITIONS). 

Stockyards  Additional  Cost 
Alone     at  West  &  S.  W. 
Activated     Plants  due  to 
Sludge  Stockyards 


TABLE  49. 


First  Cost: 

(1)  Intercepters   . . 

(2)  Disposal  Plant 


$  7,804,000 


Tanks  &  Filters 
$  472,000 
4,028,000 


Total   

Annual  Cost: 

Interest  @  4% 
Depreciation  . . 
Operation   


$  7,804,000 


$  5,500,000 


.  ..$     312,192       $  220,000 
@  4%  312,192   @  2%  110,000 
552,600*  206,000 


Total  Annual  Costs  $  1,176,984  I 

Savings : 

(1)  In  first  cost  ' 

(3)  In  Annual  Cost  

(3)  In  Operation  

(4)  In  operation  capitalized  @  4%  plus  saving  in  First 


$  436,000 


$  2,304,000 
740,984 
346,600 


Cost 


10,969,800 


♦Includes  credit  for  sale  of  36,000  tons  of  sludge  at  $10.00  per  ton. 


191 


of  3,000,000  gallons  per  acre  per  day  by  increasing  the  depth  of  the 
stone  filters  to  eight  feet. 

With  this  as  a  basis  we  have  made  a  study  of  the  savings  which 
might  be  effected  by  combining  the  Stockyards  wastes  with  the  West 
and  Southwest  Side  plants,  the  results  of  which  are  shown  in  Table  49. 

It  will  be  noted  that  the  saving  in  first  cost  is  $2,304,000,  based  on 
1935  conditions.  It  will  somewhat  exceed  this  amount  based  upon  1945 
conditions.  This  is  also  based  upon  the  use  of  eight  foot  instead  of  six 
and  one-half  foot  stone  beds.  If  it  were  found  practicable  to  use  the 
six  and  one-half  foot  depth,  as  is  quite  possible,  the  saving  would  be 
further  increased  by  $1,200,000. 

Due  to  the  elim.ination  of  the  costly  operation  of  the  activated 
sludge  plant  at  the  Stockyards  (which  is  estimated  to  be  $91,600  per 
year  in  1935,  exclusive  of  the  credit  from  the  sale  of  sludge)  and  the 
substitution  therefore  of  the  less  costly  treatment  by  stone  filters,  there 
will  be  a  saving  in  operating  cost  of  $346,600  per  year.  This  saving, 
capitaHzed  at  four  percent  and  added  to  the  saving  in  first  cost,  shows 
a  total  saving  of  $10,969,800  with  eight  foot  filters  and  $12,169,800 
with  six  and  one-half  foot  filters,  which  might  be  effected  by  combining 
the  Stockyards  sewage  Avith  that  of  the  West  and  Southwest  plants,  and 
treating  it  by  tanks  followed  by  sprinkHng  filters  rather  than  by  the 
activated  sludge  method. 

It  must  be  pointed  out  that  if  this  procedure  were  to  be  adopted  all 
of  the  grease  and  coarse  soHds  possible  should  be  recovered  before 
turning  the  wastes  into  the  intercepting  sewer.  It  might  be  accom- 
plished by  screening  or  short  tankage  with  Dorr  Clarifiers  which  for  this 
investigation  it  has  been  assumed  would  be  built  and  operated  by  the 
industries. 

This  procedure  offers  possibility  of  savings  which  are  so  large  and 
so  important  to  the  Sanitary  District,  as  well  as  to  the  Stockyards  inter- 
ests, that  they  are  certainly  worthy  of  more  investigation  than  we  have 
been  able  to  give  to  the  subject. 

Even  if  the  Stockyards  were  to  pay  half  the  cost  of  the  treatment 
plant,  their  share  of  that  cost  being  understood  to  be  approximately 
$4,000,000,  that  contribution  would  little  more  than  offset  the  saving  in 
construction  cost  that  could  be  effected,  if  the  procedure  outlined  herein 
is  practicable.  In  addition,  the  saving  in  operating  expense  would  be 
$346,600  per  year  which  is  four  percent  interest  on  over  $8,500,000  so 
that  considered  broadly,  and  on  the  investment  basis,  the  Sanitary  Dis- 
trict would  be  giving  up  $11,000,000  to  $12,000,000  as  compared  to  re- 
ceiving fifty  percent  share  of  a  separate  plant  built  to  handle  the  pack- 
inghouse wastes. 


192 


This  procedure  is  suggestive  of  the  possibility  of  important  sav- 
ings, and  by  a  method  which,  in  our  opinion,  offers  considerable  assur- 
ance of  being  practicable,  particularly  as  this  investigation  shoves  the 
necessity  for  building  the  West  and  Southwest  side  plants  at  an  early 
date. 

Period  Required  for  Construction: 

Our  instructions  include  the  determination  of  the  time  that  reason- 
ably would  be  required  to  build  the  necessary  works  and  place  them  in 
operation.  We  are  instructed  to  disregard  the  ability  to  raise  funds, 
namely,  to  assume  that  funds  would  be  available  as  needed.  We  inter- 
pret this  instruction  to  require  the  development  of  a  program  which 
shall  be  as  rapid  as  possible  and  yet  not  so  rapid  as  to  be  wasteful.  The 
effect  of  varying  the  amount  of  diluting  water  upon  the  magnitude  of 
the  construction  undertaking  is  not  sufficient  in  amount  to  have  any 
material  effect  upon  the  length  of  the  construction  period  required.  We 
have  therefore  limited  this  consideration  of  time  required  for  construc- 
tion to  one  flow,  viz,  6,000  c.  f.  s. 

The  following  is  a  summarization  of  the  expenditures  required  for 
the  6,000  cubic  feet  per  second  flow. 


Construction  Estimated  Cost 

Item.  to  1935- 

Des  Plaines  Plant  .$  264,700 

Calumet  Plant   1,564,420 

North  Side  Plant   5,600,800 

Argo  Plant    2,544,200 

Stockyards  Plant    7,804,800 

West  Side  Plant   21,431,700 

Southwest  Side  Plant   13,793,500 

Miscellaneous  Plant    3,338,620 

West  Side  Intercepter   7,890,600 

Southwest  Side  Intercepter   4,495,700 


$68,729,040 

The  total  expenditure  of  nearly  $69,000,000  required  for  1935  is, 
as  above  shown,  to  be  divided  $12,386,300  for  intercepting  sewers  and 
$56,342,740  for  seven  major  and  several  smaller  disposal  plants. 

The  intercepting  sewers  cover  a  length  of  approximately  thirty-five 
miles.  In  constructing  the  North  Side  intercepting  sewers  the  Nash 
contract  covering  four  miles,  and  an  aggregate  expenditure  of  $1,998,000 
was  executed  in  one  year.  Five  contracts  aggregating  ten  miles  and  an 
expenditure  of  $5,488,000  were  completed  in  two  years. 


193 


We  have  assembled  the  data  relative  to  construction  progress  on 
Sanitary  District  contracts  and  also  on  other  public  or  semi-public  con- 
struction of  large  magnitude,  as  shown  in  summarized  form  on  Table  50. 

It  will  be  noticed  from  this  table  that  construction  progress  of  a  type 
comparable  to  sewage  disposal  plants  has  been  rapid  in  many  cases. 
The  construction  of  the  Chicago  Produce  Market  at  a  cost  of  $17- 
000,000  in  approximately  six  months'  time,  is  a  most  striking  illustra- 
tion of  what  can  be  accomplished  in  the  way  of  rapid  construction  of  a 
type  consisting  largely  of  duplicate  units,  such  as  is  also  the  case  with 
sewage  disposal  plants. 

Based  upon  the  progress  on  prior  Sanitary  District  contracts  and 
elsewhere  there  should  be  no  difficulty  in  building  the  twenty  miles  of 
West  Side  intercepters  and  the  fifteen  miles  of  Southwest  Side  inter- 
cepters  so  as  to  be  finished  by  the  end  of  1930.  This  would  require  less 
than  double  the  progress  secured  on  the  North  Side  intercepters. 

The  expenditures  for  the  Des  Plaines,  Calumet  and  North  side 
plant  enlargements  can  all  be  finished  in  the  next  two  or  three  years. 
So  far  as  disposal  plants  are  concerned,  the  real  question  as  to  time 
therefore  hinges  upon  the  Argo,  Stockyards,  West  and  Southwest  side 
plants. 

The  Sanitary  District  in  arranging  its  program  of  design  and  con- 
struction has  estimated  that  the  West  side  plant,  including  tanks  and 
sludge  handling  facilities,  can  be  completed  by  December,  1929.  We 
see  no  reason  why,  if  plants  are  started  promptly,  the  construction  of  the 
stone  sprinkling  filters  for  the  secondary  treatment  cannot  be  completed 
within  a  year  thereafter,  viz.  December,  1930,  and  possibly  simultan- 
eously with  the  tanks. 

The  Southwest  side  involves  construction  similar  to  that  at  the 
West  side,  but  only  approximately  two-thirds  as  great  in  amount.  It 
should,  therefore,  be  practicable  to  design  and  build  the  southwest  side 
plant  so  that  it  will  be  finished  without  difficulty  by  the  end  of  1930. 

The  Argo  and  Corn  Products  plants  are  comparatively  small,  al- 
though they  involve  a  more  thorough  study  of  experimental  work  and 
a  more  complicated  design  than  is  required  for  the  West  and  South- 
west side  plants.  It  is  believed,  however,  that  they  can  be  designed  and 
built  so  as  to  be  ready  for  operation  by  1930. 

Summarisation  of  the  Construction  Period  Reasonably  Required: 

It  would  be  our  opinion  that  five  years'  time,  under  average  con- 
struction conditions,  would  be  a  reasonable  minimum  estimate  of  the 
time  required  to  design  and  build  the  intercepters  and  sewage  treatment 
plants  at  the  costs  herein  outhned.    Even  with  .the  most  unfavorable 


194 


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construction  conditions,  the  contingency  of  labor  troubles,  and  similar 
delays,  we  can  see  no  reason  why  the  period  should  exceed  eight  to  ten 
years. 

All  of  the  above  is  predicated  upon  the  ability  of  the  Sanitary  Dis- 
trict to  finance  the  program  within  the  construction  period. 

A  ckn  owledgm  ent: 

In  the  preparation  of  this  report  the  Sanitary  District  of  Chicago 
has  furnished  to  us  numerous  data  and  studies  bearing  upon  the  prob- 
lems here  considered.  There  has  also  been  placed  at  our  disposal  the 
valuable  studies. of  the  U.  S.  Public  Health  Service  relating  to  the 
Des  Plaines  and  Illinois  Rivers,  which  we  have  freely  used.  The 
Illinois  State  Water  Survey  has  furnished  many  valuable  data  relating 
to  the  past  conditions  in  the  downstream  rivers,  and  we  are  particularly 
indebted  to  the  Illinois  State  Natural  History  Survey  for  information 
on  the  same  streams,  particularly  relating  to  the  welfare  of  fishwife. 

In  connection  with  our  work  we  have  been  assisted  by  Mr.  Clarence 
B.  Hoover,  Superintendent,  Division  of  Water  and  Sewage  Disposal, 
Columbus,  Ohio,  a  practical  sewage  plant  operator  for  the  past  sixteen 
years.  We  have  also  been  assisted  by  Mr.  T.  McLean  Jasper,  Research 
Laboratory,  University  of  Illinois. 

Respectfully  submitted, 
ALVORD,  BURDICK  &  HOWSON, 
(Signed)  Chas.  B,  Buedick, 

(Signed)  L.  R.  Howson, 

Chicago,  Illinois, 
April  16,  1925. 


PUBLICATIONS  OF  THE  STATE  WATER  SURVEY. 


No.  1-9.  Out  of  print. 

No.  10.  Chemical  and  biological  survey  of  the  waters  of  Illinois 
Report  for  1912.    198  pp.,  19  cuts. 

No.  11.  Chemical  and  biological  survey  of  the  waters  of  Illinois. 
Report  for  1913.    473  pp.,  106  cuts. 

No.  12.  Chemical  and  biological  survey  of  the  waters  of  Illinois. 
Report  for  1914.    261  pp.,  32  cuts. 

No.  13.  Chemical  and  biological  survey  of  the  waters  of  Illinois. 
Report  for  1915.    381  pp.,  36  cuts. 

No.  14.  Chemical  and  biological  survey  of  the  waters  of  Illinois. 
Report  for  1916.    192  pp.,  40  cuts. 

No.  15.  Chemical  and  biological  survey  of  the  waters  of  Illinois. 
Report  for  1917.   136  pp.,  8  cuts. 

No.  16.  Chemical  and  biological  survey  of  the  waters  of  Illinois. 
Report  for  1918  and  1919.    280  pp.,  36  cuts. 

No.  17.    Index  to  Bulletins  1-16.    1921.    17  pp. 

No.  18.    Activated  sludge  studies,  1920-1922.    150  pp.,  31  cuts. 

No.  19.    Solubility  and  rate  of  solution  of  gases.  Bibliography. 
1924.    49  pp. 

No.  20.  Comparison  of  chemical  and  bacteriological  examina- 
tions made  on  the  Illinois  River  during  a  season  of 
low  water  and  a  season  of  high  water — 1923-1924, 
33  pp.,  4  cuts. 

• 

A  preliminary  notice  of  a  survey  of  the  sources  of  pol- 
lution of  the  streams  of  Illinois.    1924.    26  pp.,  4  cuts. 

No.  21.  Public  ground-water  supplies  ,  in  Illinois.  1925.  710  pp., 
11  cuts.    (Price  $1.00.) 

No.  22.  Investigations  of  chemical  reactions  involved  in  water 
purification,  1920-1925.    133  pp.,  17  cuts.    (Price  75c.) 


For  copies  of  these  l)ulletins  or  for  other  information  address  - 
Chief,  State  Water  Survey,  Urbana,  Illinois. 


